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new 5203282 Created a markdown listing of possible schema definition
errors that can occur while developing a DFDL schema. The listing is based on
the Apache Daffodil Specification.
5203282 is described below
commit 52032824e362f477c39d8aa6aaf1b7fab724a905
Author: rthomas320 <[email protected]>
AuthorDate: Wed Oct 22 08:03:36 2025 -0400
Created a markdown listing of possible schema definition errors that can
occur while developing a DFDL schema. The listing is based on the Apache
Daffodil Specification.
Closes #1308
---
.prettierignore | 1 +
project/Rat.scala | 2 +
.../dfdl-xref/DFDL_Schema_Definition_Errors.md | 1436 ++++++++++++++++++++
3 files changed, 1439 insertions(+)
diff --git a/.prettierignore b/.prettierignore
index e80ad57..9842a28 100644
--- a/.prettierignore
+++ b/.prettierignore
@@ -20,3 +20,4 @@ out
dist
src/language/dfdl-xref/*.htm
src/language/dfdl-xref/DFDL_XRef_files/*.htm
+
diff --git a/project/Rat.scala b/project/Rat.scala
index 4e80008..e8b214e 100644
--- a/project/Rat.scala
+++ b/project/Rat.scala
@@ -66,7 +66,9 @@ object Rat {
file("src/language/dfdl-xref/DFDL_ElementXRef.md"),
file("src/language/dfdl-xref/DFDL_ElementAnnotationXRef.md"),
file("src/language/dfdl-xref/DFDL_PropertyXRef.md"),
+ file("src/language/dfdl-xref/DFDL_Schema_Definition_Errors.md"),
file("src/language/dfdl-xref/html/DFDL_XRef.htm"),
+ file("src/language/dfdl-xref/DFDL_Schema_Definition_Errors.md"),
file("src/language/dfdl-xref/html/DFDL_XRef_files/filelist.xml"),
file("src/language/dfdl-xref/html/DFDL_XRef_files/sheet001.htm"),
file("src/language/dfdl-xref/html/DFDL_XRef_files/sheet002.htm"),
diff --git a/src/language/dfdl-xref/DFDL_Schema_Definition_Errors.md
b/src/language/dfdl-xref/DFDL_Schema_Definition_Errors.md
new file mode 100644
index 0000000..3a50b3f
--- /dev/null
+++ b/src/language/dfdl-xref/DFDL_Schema_Definition_Errors.md
@@ -0,0 +1,1436 @@
+**_Schema Definition Error_** or **_SDE_** for short - these indicate
+the DFDL schema is not meaningful. They are generally fatal errors that
+prevent or stop processing of data.
+
+5.3.2 **MinLength, MaxLength**
+
+These facets are used:
+
+- When dfdl:lengthKind is \"implicit\" and type is xs:string or
+ xs:hexBinary. In that case the length is given by the value of the XSD
+ maxLength facet. In this case the XSD minLength facet is required to
+ be equal to the XSD maxLength facet (Schema Definition Error
+ otherwise).
+
+- For validation of variable length string elements.
+
+ 6.3.4 **Enumerations in DFDL**
+
+Some DFDL properties accept an enumerated list of valid values. It is a
+Schema Definition Error if a value other than one of the enumerated
+values is specified. The case of the specified value must match the
+enumeration. An enumeration is of type string unless otherwise stated.
+
+7.1.1 **Property Binding Syntax**
+
+A _property binding_ is the syntax in a DFDL schema that gives a value
+to a property. Up to this point, the examples in this document have all
+used a specific syntax for property bindings called _attribute form_.
+However, the format properties may be specified in any one of three
+forms:
+
+1. Attribute form
+
+2. Element form
+
+3. Short form
+
+A DFDL property may be specified using any of the forms with the
+following exceptions:
+
+- The dfdl:ref property may be specified in attribute or short form
+
+- The dfdl:escapeSchemeRef property may be specified in attribute or
+ short form
+
+- The dfdl:hiddenGroupRef property may be specified in attribute or
+ short form
+
+- The dfdl:prefixLengthType property may be specified in attribute or
+ short form
+
+- Short form must not be used on the xs:schema element.
+
+It is a Schema Definition Error if the same property is specified in
+more than one form. That is, there is no priority ordering where one
+form takes precedent over another.
+
+7.1.2 **Empty String as a Representation Property Value**
+
+DFDL provides no mechanism to un-set a property. Setting a
+representation property\'s value to the empty string doesn\'t remove the
+value for that property but sets it to the empty string value. This may
+not be a valid value for certain properties. In non-delimited text data
+formats, it is sensible for the separator to be defined to be the empty
+string. This turns off use of separator delimiters. For many other
+string-valued properties, it is a Schema Definition Error to assign them
+the empty string value. For example, the character set encoding property
+(dfdl:encoding) cannot be set to the empty string.
+
+**.2 dfdl:defineFormat - Reusable Data Format Definitions**
+
+To avoid error-prone redundant expression of properties in DFDL schemas,
+a collection of DFDL properties can be given a name so that they are
+reusable by way of a _format reference_.
+
+One or more dfdl:defineFormat annotation elements can appear within the
+annotation children of the xs:schema element.
+
+Each dfdl:defineFormat has a required name attribute.
+
+The construct creates a named data format definition. The value of the
+name attribute is of XML type NCName. The format name becomes a member
+of the schema\'s target namespace. These names must be unique within the
+namespace.
+
+If multiple format definitions have the same \'name\' attribute, in the
+same namespace, then it is a Schema Definition Error.
+
+It is a Schema Definition Error if use of the dfdl:ref property results
+in a circular path.
+
+\*TODO\* not sure where this \^ should go.
+
+**7.3 The dfdl:defineEscapeScheme Defining Annotation Element**
+
+One or more dfdl:defineEscapeScheme annotation elements can appear
+within the annotation children of the xs:schema. It is a Schema
+Definition Error if use of the dfdl:ref property results in a circular
+path.
+
+7.5.1 **Properties for dfdl:assert**
+
+A dfdl:assert annotation contains a test expression or a test pattern.
+
+It is a Schema Definition Error if a test expression or test pattern is
+specified in more than one form.
+
+It is a Schema Definition Error if both a test expression and a test
+pattern are specified.
+
+The testKind property specifies whether an expression or pattern is used
+by the dfdl:assert. The expression or pattern can be expressed as an
+attribute or as a value.
+
+It is a Schema Definition Error if testKind is \'expression\' or not
+specified, and an expression is not supplied by either the value of the
+dfdl:assert element or the value of the test attribute.
+
+testPattern A DFDL regular expression that is applied against the data
+stream starting at the data position corresponding to the beginning of
+the representation. Applies when testKind is \'pattern\'.
+
+If the length of the match is zero then the dfdl:assert evaluates to
+false and a Processing Error is raised.
+
+If the length of the match is non-zero then the dfdl:assert evaluates to
+true.
+
+If a Processing Error occurs during the evaluation of the test regular
+expression then the dfdl:assert also fails.
+
+It is a Schema Definition Error if testKind is \'pattern\', and a
+pattern is not supplied by either the value of the dfdl:assert element
+or the value of the testPattern property.
+
+It is a Schema Definition Error if there is no value for the
+dfdl:encoding property in scope.
+
+It is a Schema Definition Error if dfdl:leadingSkip is other than 0.
+
+It is a Schema Definition Error if the dfdl:alignment is not 1 or
+\'implicit\'
+
+If a Processing Error or Schema Definition Error occurs while evaluating
+the message expression, a Recoverable Error is issued to record this
+error (containing implementation-dependent content), then processing of
+the assert continues as if there were no problem and in a manner
+consistent with the failureType property, but using an
+implementation-dependent substitute message.
+
+7.6.1 **Properties for dfdl:discriminator**
+
+Within a dfdl:discriminator, the testKind property specifies whether an
+expression or pattern is used by the dfdl:discriminator. The expression
+or pattern can be expressed as an attribute or as a value.
+
+It is a Schema Definition Error if the test expression or test pattern
+is specified in more than one form.
+
+It is a Schema Definition Error if both a test expression and a test
+pattern are specified.
+
+It is a Schema Definition Error if testKind is \'expression\' or not
+specified, and an expression is not supplied by either the value of the
+dfdl:discriminator element or the value of the test attribute.
+
+It is a Schema Definition Error if testKind is \'expression\' or not
+specified, and an expression is not supplied by either the value of the
+dfdl:discriminator element or the value of the test attribute.
+
+If the length of the match is zero then the dfdl:discriminator evaluates
+to false and a Processing Error is raised.
+
+If the length of the match is non-zero then the dfdl:discriminator
+evaluates to true.
+
+It is a Schema Definition Error if testKind is \'pattern\', and a
+pattern is not supplied by either the value of the dfdl:discriminator
+element or the value of the testPattern property.
+
+It is a Schema Definition Error if there is no value for the
+dfdl:encoding property in scope.
+
+It is a Schema Definition Error if dfdl:leadingSkip is other than 0.
+
+It is a Schema Definition Error if the dfdl:alignment is not 1 or
+\'implicit\'
+
+If a Processing Error or Schema Definition Error occurs while evaluating
+the message expression, a Recoverable Error is issued to record this
+error (containing implementation-dependent content), then processing of
+the discriminator continues as if there were no problem, but in the case
+of failure using an implementation-dependent substitute message.
+
+The resolved set of statement annotations for a schema component can
+contain only a single dfdl:discriminator or one or more dfdl:assert
+annotations, but not both. It is a Schema Definition Error otherwise. A
+defaultValue is optional.
+
+Note that the syntax supports both a defaultValue attribute and the
+default value being specified by the element value. Only one or the
+other may be present otherwise it is a Schema Definition Error.
+
+A defaultValue expression can refer to other variables but not to the
+Infoset. When a defaultValue expression references other variables, the
+referenced variables each must either have a defaultValue or be
+external. It is a Schema Definition Error otherwise.
+
+7.7.1 **dfdl:defineVariable Annotation Element**
+
+The name of a newly defined global variable is placed into the target
+namespace of the schema containing the annotation. A variable can have
+any type from the DFDL subset of XML schema simple types. If no type is
+specified, the type is xs:string. A defaultValue is optional. The
+default value must match the type of the variable (otherwise it is a
+Schema Definition Error). If the defaultValue is given by an expression
+that expression must not contain any relative path (otherwise it is a
+Schema Definition Error).
+
+Note also that the value of the name attribute is an NCName (non-colon
+name - that is, may not have a prefix). The name of a variable is
+defined in the target namespace of the schema containing the definition.
+If multiple dfdl:defineVariable definitions have the same \'name\'
+attribute in the same namespace then it is a Schema Definition Error.
+
+If a defaultValue expression references another variable and this causes
+a circular reference, it is a Schema Definition Error.
+
+It is a Schema Definition Error if the type of the variable is a
+user-defined simple type restriction.
+
+7.7.2 **The dfdl:newVariableInstance Statement Annotation Element**
+
+Scoped instances of defined variables are created using
+dfdl:newVariableInstance. All instances share the same name, type, and
+default value if provided, but they have distinct storage for separate
+values using a stack-like mechanism where a new instance is introduced
+for a model group. These new instances are associated with a schema
+component using dfdl:newVariableInstance.
+
+The dfdl:newVariableInstance annotation can be used on a group
+reference, sequence or choice only. It is a Schema Definition Error
+otherwise.
+
+Note that the syntax supports both a defaultValue attribute and the
+default value being specified by the annotation element value. Only one
+or the other may be present it is a Schema definition error otherwise.
+
+The resolved set of annotations for a component may contain multiple
+dfdl:newVariableInstance statements. They must all be for unique
+variables; it is a Schema Definition Error otherwise.
+
+7.7.3 **The dfdl:setVariable Statement Annotation Element**
+
+Variable instances get their values either by default, by external
+definition, or by subsequent assignment using the dfdl:setVariable
+statement annotation.
+
+The dfdl:setVariable annotation can be used on a simple type, group
+reference, sequence or choice. It may be used on an element or element
+reference only if the element is of simple type. It is a Schema
+Definition Error if dfdl:setVariable appears on an element of complex
+type, or an element reference to an element of complex type.
+
+The syntax supports both a value attribute and the \'value\' being
+specified by the element value. Only one or the other may be present
+otherwise it is a Schema Definition Error.
+
+The value of an instance can only be set once using dfdl:setVariable.
+Attempting to set the value of the variable instance for a second time
+is a Schema Definition Error.
+
+The resolved set of annotations for an annotation point may contain
+multiple dfdl:setVariable statements. They must all be for unique
+variables (different name and/or namespace) it is a Schema Definition
+Error otherwise.
+
+8.1.3 **Combining DFDL Representation Properties from a
+dfdl:defineFormat**
+
+The DFDL representation properties contained in a referenced
+dfdl:defineFormat are combined with any DFDL representation properties
+defined locally on a construct as if they had been defined locally. If
+the same property is defined locally in and in the
+referenced.dfdl:defineFormat then the local property takes precedence.
+The combined set of explicit DFDL properties has precedence over any
+defaults set by a dfdl:format on the xs:schema.
+
+It is a Schema Definition Error if a required property is in neither the
+\"explicit\" nor the \"default\" working sets.
+
+It is a Schema Definition Error if the same property appears twice.
+
+**10 Overview: Representation Properties and their Format Semantics**
+
+It is a Schema Definition Error when a DFDL schema does _not_ contain a
+definition for a representation property that is needed to interpret the
+data.
+
+**11.3 Byte Order and Bit Order**
+
+Byte order and bit order are separate concepts. However, of the possible
+combinations, only the following are allowed:
+
+1. 'bigEndian' with 'mostSignificantBitFirst'
+
+2. 'littleEndian' with 'mostSignificantBitFirst'
+
+3. 'littleEndian' with 'leastSignificantBitFirst'
+
+Other combinations will produce Schema Definition Errors.
+
+12.1.2 **Mandatory Alignment for Textual Data**
+
+When processing textual data, it is a Schema Definition Error if the
+dfdl:alignment and dfdl:alignmentUnits properties are used to specify
+alignment that is not a multiple of the encoding-specified mandatory
+alignment.
+
+12.1.3 **Mandatory Alignment for Packed Decimal Data**
+
+Packed decimal data is data with
+dfdl:binaryNumberRep[\[37\]](https://daffodil.apache.org/docs/dfdl/#_ftn37)
+values of \'packed\', \'ibm4690Packed\' or \'bcd\'. This representation
+stores a decimal digit in a 4 bit nibble. These nibbles must have a
+multiple of 4-bit alignment. It is a Schema Definition Error otherwise.
+
+**12.2 Properties for Specifying Delimiters**
+
+The Initiator property can be computed by way of an expression which
+returns a string containing a whitespace separated list of DFDL String
+Literals. It is a Schema Definition Error to return an empty string or a
+string containing only whitespace.
+
+Each string literal in the list, whether apparent in the schema, or
+returned as the value of an expression, is restricted to allow only
+certain kinds of DFDL String Literal syntax:
+
+· DFDL character entities are allowed.
+
+· DFDL Byte Value entities ( %#rXX; ) are allowed.
+
+· DFDL Character Classes NL, WSP, WSP+, WSP\*, and ES are
+allowed.
+
+· If the ES entity or the WSP\* entity appear alone as one of
+the string literals in the list, then dfdl:initiatedContent must be
+\"no\". This restriction ensures that when dfdl:initiatedContent is
+\'yes\' that the initiator cannot match zero-length data.
+
+If the above rules are not followed it is a Schema Definition Error.
+
+A terminator specifies an ordered whitespace separated list of
+alternative text strings that one of which marks the end of an element
+or group of elements.
+
+Each string literal in the list, whether apparent in the schema, or
+returned as the value of an expression, is restricted to allow only
+certain kinds of DFDL String Literal syntax:
+
+· DFDL character entities are allowed.
+
+· DFDL Byte Value entities ( %#rXX; ) are allowed.
+
+· DFDL Character Classes NL, WSP, WSP+, WSP\*, and ES are
+allowed.
+
+· Neither the ES entity nor the WSP\* entity may appear on their
+own as one of the string literals in the list when the parser is
+determining the length of a component by scanning for delimiters.
+
+If the above rules are not followed it is a Schema Definition Error.
+
+If dfdl:terminator is \"\" (the empty string), that is the way a DFDL
+schema expresses a format which does not use terminators. It is a Schema
+Definition Error for a terminator expression to return an empty string
+
+The emptyValueDelimiterPolicy Indicates that when an element in the data
+stream is empty, which of initiator, terminator, both, or neither must
+be present.
+
+It is a Schema Definition Error if dfdl:emptyValueDelimiterPolicy set to
+\'none\' or \'terminator\' when the parent group has
+dfdl:initiatedContent \'yes\'.
+
+If there is a dfdl:initiator or dfdl:terminator in scope, and
+dfdl:emptyValueDelimiterPolicy is not set, it is a Schema Definition
+Error.
+
+f dfdl:initiator is not \"\" and dfdl:terminator is \"\" and
+dfdl:emptyValueDelimiterPolicy is \'terminator\' it is a Schema
+Definition Error.
+
+If dfdl:terminator is not \"\" and dfdl:initiator is \"" and
+dfdl:emptyValueDelimiterPolicy is \'initiator\' it is a Schema
+Definition Error. It is a Schema Definition Error if
+dfdl:emptyValueDelimiterPolicy is in effect and is set to \'none\' or
+\'terminator\' when the parent xs:sequence has dfdl:initiatedContent
+\'yes\'.
+
+Note: It is not a Schema Definition Error if
+dfdl:emptyValueDelimiterPolicy is \'both\' and one or both of
+dfdl:initiator and dfdl:terminator is \"\". This is to accommodate the
+common use of setting \'both\' as a schema-wide setting.
+
+The outputNewLine DFDL String Literal or DFDL Expression specifies the
+character or characters that are used to replace the %NL; character
+class entity during unparse.
+
+It is a Schema Definition Error if any of the characters are not in the
+set of characters allowed by the DFDL entity %NL; Only individual
+characters or the %CR;%LF; combination are allowed.
+
+It is a Schema Definition Error if the DFDL entity %NL; is specified.
+
+12.3.3 **dfdl:lengthKind \'implicit\'**
+
+When dfdl:lengthKind is \'implicit\', the length is determined in terms
+of the type of the element and its schema-specified properties.
+
+A dfdl:lengthKind property of \'Not Allowed\' means that there is no
+implicit length for the combination of simple type and representation,
+and it is a Schema Definition Error if dfdl:lengthKind \'implicit\' is
+specified
+
+It is a Schema Definition Error if type is xs:string and dfdl:lengthKind
+is \'implicit\' and dfdl:lengthUnits is \'bytes\' and encoding is not an
+SBCS (exactly 1 byte per character code) encoding.
+
+12.3.4 **dfdl:lengthKind \'prefixed\'**
+
+When dfdl:lengthKind is \'prefixed\' the length of the element is given
+by the integer value of the PrefixLength region specified using
+dfdl:prefixLengthType.
+
+It is a Schema Definition Error if prefixLengthType of xs:simpleType
+pecifies any of:
+
+- dfdl:lengthKind \'delimited\', \'endOfParent\', or \'pattern\'
+
+- dfdl:lengthKind \'explicit\' where length is an expression
+
+- dfdl:outputValueCalc
+
+- dfdl:initiator or dfdl:terminator other than empty string
+
+- dfdl:alignment other than \'1\'
+
+- dfdl:leadingSkip or dfdl:trailingSkip other than \'0
+
+ 12.3.4.1 **Nested Prefix Lengths**
+
+It is possible for a prefix length, as specified by
+dfdl:prefixLengthType, to itself have a prefix length. It is a Schema
+Definition Error if this nesting exceeds 1 deep.
+
+It is a Schema Definition Error unless the type associated with the
+PrefixPrefixLength is different from the type associated with the
+PrefixLength.
+
+The DFDL Regular Expression lengthPattern is only used when lengthKind
+is 'pattern'.
+
+It is a Schema Definition Error if there is no value for the
+dfdl:encoding property in scope
+
+12.3.6 **dfdl:lengthKind \'endOfParent\'**
+
+The dfdl:lengthKind \'endOfParent\' means that the element is terminated
+either by the end of the data stream, or the end of an enclosing complex
+element with dfdl:lengthKind 'explicit', 'pattern', 'prefixed' or
+'endOfParent', or the end of an enclosing choice with
+dfdl:choiceLengthKind 'explicit'.
+
+It is a Schema Definition Error if:
+
+· the element has a terminator.
+
+· the element has dfdl:trailingSkip not equal to 0.
+
+· the element has maxOccurs \> 1.
+
+· any other model-group is defined between this element and the
+end of the enclosing component.
+
+· any other represented element is defined between this element
+and the end of the enclosing component.
+
+· the parent is an element with dfdl:lengthKind \'implicit\' or
+\'delimited\'.
+
+· the element has text representation, does not have a
+single-byte character set encoding, and the effective length units of
+the parent is not 'characters'.
+
+· The effective length units of the parent are:
+
+> o dfdl:lengthUnits if parent is an element with dfdl:lengthKind
+> 'explicit' or 'prefixed';
+>
+> o 'characters' if parent is an element with dfdl:lengthKind
+> 'pattern';
+>
+> o 'bytes' if parent is a choice with dfdl:choiceLengthKind
+> 'explicit';
+>
+> o 'characters' if the element is the document root;
+>
+> o the effective length units of the parent's parent if parent is an
+> element with dfdl:lengthKind 'endOfParent'
+
+If the element is in a sequence then it is a Schema Definition Error if:
+
+· the dfdl:separatorPosition of the sequence is \'postfix\'
+
+· the dfdl:sequenceKind of the sequence is not \'ordered\'
+
+· the sequence has a terminator
+
+· there are floating elements in the sequence
+
+· the sequence has a non-zero dfdl:trailingSkip
+
+If the element is in a choice where dfdl:choiceLengthKind is
+\'implicit\' then it is a Schema Definition Error if:
+
+· the choice has a terminator
+
+· the choice has a non-zero dfdl:trailingSkip
+
+12.3.7 **Elements of Specified Length**
+
+An element has a specified length when dfdl:lengthKind is \'explicit\',
+\'implicit\' (simple type only) or \'prefixed\'.
+
+For a simple element, dfdl:lengthUnits \'characters\' may only be used
+for textual elements, otherwise it is a Schema Definition Error.
+
+**12.3.7.1.1 Text Length Specified in Bytes**
+
+If a textual element has dfdl:lengthUnits of \'bytes\', and the
+dfdl:encoding is not SBCS, then it is possible for a partial character
+encoding to appear after the code units of the characters.
+
+It is a Schema Definition Error if type is xs:string and
+dfdl:textPadKind is not \'none\' and dfdl:lengthUnits is \'bytes\' and
+dfdl:encoding is not an SBCS encoding and the XSD minLength facet is not
+zero. This prevents a scenario where validation against the XSD
+minLength facet is in characters, but padding would be performed in
+bytes.
+
+12.3.7.2 **Length of Simple Elements with Binary Representation**
+
+The dfdl:lengthKind properties \'explicit\' and \'prefixed\' specify
+lengths for the different binary representations. When dfdl:lengthKind
+is \'implicit\' the dfdl:lengthUnits can be \'bytes\' or \'bits\' unless
+otherwise stated. It is Schema Definition Error if dfdl:lengthUnits is
+\'characters\'.
+
+he dfdl:lengthUnits can be \'bytes\' or \'bits\' unless otherwise
+stated. It is Schema Definition Error if dfdl:lengthUnits is
+\'characters\'.
+
+**12.3.7.2.2 Length of Floating Point Binary Number Elements**
+
+For binary elements of types xs:float or xs:double, a specified length
+must be either exactly 4 bytes or exactly 8 bytes respectively.
+
+The dfdl:lengthUnits property must be \'bytes\'. It is a Schema
+Definition Error otherwise.
+
+**12.3.7.2.3 Length of Packed Decimal Number Elements**
+
+Non-floating-point numbers with binary representation and
+dfdl:binaryNumberRep \'packed\', \'bcd\', or \'ibm4690Packed\', are
+represented as a bit string of 4 bit nibbles. The term _packed decimal_
+is used to describe such numbers.
+
+It is a Schema Definition Error if the specified length is not a
+multiple of 4 bits.
+
+**12.3.7.2.5 Length of Base-2 Binary Calendar Elements**
+
+Calendars (types date, time, dateTime) with binary representation and
+dfdl:binaryCalendarRep 'binarySeconds' or 'binaryMilliseconds' are
+represented as a bit string which contains a base-2 representation. The
+specified length must be either exactly 4 bytes or exactly 8 bytes
+respectively.
+
+The dfdl:lengthUnits property must be \'bytes\'. It is a Schema
+Definition Error otherwise.
+
+**12.3.7.2.6 Length of Packed Decimal Calendar Elements**
+
+Calendars (types date, time, dateTime) with binary representation and
+dfdl:binaryCalendarRep \'packed\', \'bcd\', or \'ibm4690Packed\', are
+represented as a bit string of 4-bit nibbles. The term _packed decimal_
+is used to describe such calendars.
+
+It is a Schema Definition Error if the specified length is not a
+multiple of 4 bits.
+
+**12.3.7.2.7 Length of Binary Opaque Elements**
+
+The dfdl:lengthUnits property must be \'bytes\'. It is a Schema
+Definition Error otherwise.
+
+12.3.7.3 **Length of Complex Elements**
+
+A complex element of specified length is defining a \'box\' in which its
+child elements exist. An example of this would be a fixed-length record
+element with a variable number of children elements. The
+dfdl:lengthUnits may be \'bytes\' or \'characters\', it is a Schema
+Definition Error otherwise.
+
+The dfdl:escapeScheme annotation is used within a
+dfdl:defineEscapeScheme annotation to group the properties of an escape
+scheme and allows a common set of properties to be defined that can be
+reused.
+
+The escapeCharacter property specifies one character that escapes the
+subsequent character.
+
+It is a Schema Definition Error if dfdl:escapeCharacter is empty when
+dfdl:escapeKind is \'escapeCharacter\'
+
+_Escape and Quoting Character Restrictions:_ The string literal is
+restricted to allow only certain kinds of DFDL String Literal syntax:
+
+- DFDL character entities are allowed
+
+- The DFDL byte value entity ( %#rXX; ) is not allowed
+
+- DFDL Character classes NL, WSP, WSP+, WSP\*, and ES are not allowed
+
+It is a Schema Definition Error if the string literal contains any of
+the disallowed constructs.
+
+The escapeBlockStart property contains the string of characters that
+denotes the beginning of a sequence of characters escaped by a pair of
+escape strings.
+
+It is a Schema Definition Error if dfdl:escapeBlockStart is empty when
+dfdl:escapeKind is \'escapeBlock\'
+
+The string literal value is restricted in the same way as described in
+\"Escape and Quoting Character Restrictions\" in the description of the
+dfdl:escapeCharacter property.
+
+The escapeBlockEnd property contains the string of characters that
+denotes the end of a sequence of characters escaped by a pair of escape
+strings.
+
+It is a Schema Definition Error if dfdl:escapeBlockEnd is empty when
+dfdl:escapeKind is \'escapeBlock\'.
+
+**13.4 Properties Specific to String**
+
+The textStringPadCharacter property contains the value that is used when
+padding or trimming string elements. The value can be a single character
+or a single byte.
+
+If a character, then it can be specified using a literal character or
+using DFDL entities.
+
+If a byte, then it must be specified using a single byte value entity
+otherwise it is a Schema Definition Error
+
+_Padding Character Restrictions:_ The string literal is restricted to
+allow only certain kinds of DFDL String Literal syntax:
+
+- DFDL character entities are allowed
+
+- The DFDL byte value entity ( %#rXX; ) is allowed.
+
+- DFDL Character classes NL, WSP, WSP+, WSP\*, and ES are not allowed
+
+It is a Schema Definition Error if the string literal contains any of
+the disallowed syntax.
+
+**13.6 Properties Specific to Number with Text Representation**
+
+The valid values for the are textNumberRep property \'standard\',
+\'zoned\'
+
+\'standard\' means represented as characters in the character set
+encoding specified by the dfdl:encoding property.
+
+\'zoned\' means represented as a zoned decimal in the character set
+encoding specified by the dfdl:encoding property.
+
+Zoned is not supported for float and double numbers. Base 10 is assumed,
+and the encoding must be for an EBCDIC or ASCII compatible encoding. It
+is a Schema Definition Error if any of these requirements are not met.
+
+The textNumberRoundingIncrement property specifies the rounding
+increment to use during unparsing, when dfdl:textNumberRounding is
+\'explicit\'.
+
+A negative value is a Schema Definition Error.
+
+The textStandardDecimalSeparator s the punctuation mark which separates
+the integer part of a decimal or floating point number from the
+fractional part. It is usually a period or comma depending on locale of
+the data. This property defines a whitespace separated list of single
+characters that appear (individually) in the data as the decimal
+separator.
+
+When dfdl:textNumberRep is \'standard\' and dfdl:textStandardBase is 10.
+It must be set if dfdl:textNumberPattern contains a decimal separator
+symbol (\".\"), or the E or @ symbols, otherwise it is a
+SchemaDefinitionError.
+
+_Text Number Character Restrictions:_ The string literal is restricted
+to allow only certain kinds of DFDL String Literal syntax:
+
+· DFDL character entities are allowed
+
+· The DFDL byte value entity ( %#rXX; ) is not allowed.
+
+· DFDL Character classes NL, WSP, WSP+, WSP\*, and ES are not
+allowed
+
+It is a Schema Definition Error if the string literal contains any of
+the disallowed syntax constructs.
+
+It is a Schema Definition Error if any of the string literal values for
+this property are digits 0-9.
+
+The textStandardGroupingSeparator is the punctuation mark which
+separates the clusters of integer digits to improve readability.
+
+This property is applicable when dfdl:textNumberRep is \'standard\' and
+dfdl:textStandardBase is 10. It must be set if dfdl:textNumberPattern
+contains a grouping separator symbol otherwise it is a Schema Definition
+Error.
+
+The textStandardExponentRep property defines the actual character(s)
+that appear in the data as the exponent indicator. If the empty string
+is specified then no exponent character is used.
+
+It is a Schema Definition Error if this property is not set or in scope
+for any number with dfdl:representation \'text\'.
+
+The textStandardInfinityRep property contains the value used to
+represent infinity.
+
+It is a Schema Definition Error if empty string found as the property
+value.
+
+The textStandardNaNRep property contains the value used to represent
+NaN.
+
+It is a Schema Definition Error if empty string found as the property
+value.
+
+The textStandardZeroRep property contains the whitespace separated list
+of alternative DFDL String Literals that are equivalent to zero. The
+valid values are empty string, any character string.
+
+Each string literal in the list is restricted to allow only certain
+kinds of DFDL String Literal syntax:
+
+· DFDL character entities are allowed.
+
+· DFDL Byte Value entities ( %#rXX; ) are not allowed.
+
+· DFDL Character class entities NL and ES are not allowed.
+
+· DFDL Character class entities WSP, WSP+, and WSP\* are
+allowed.
+
+However, the WSP\* entity cannot appear on its own as one of the string
+literals in the list. It must be used in combination with other text
+characters or entities so as to describe a representation that cannot
+ever be an empty string.
+
+It is a Schema Definition Error if the string literal contains any of
+the disallowed syntax constructs.
+
+Annotation: dfdl:element, dfdl:simpleType
+
+13.6.1 **The dfdl:textNumberPattern Property**
+
+The dfdl:textStandardDecimalSeparator,
+dfdl:textStandardGroupingSeparator, dfdl:textStandardExponentRep,
+dfdl:textStandardInfinityRep, dfdl:textStandardNaNRep, and
+dfdl:textStandardZeroRep must all be distinct, and it is a Schema
+Definition Error otherwise.
+
+13.6.1.1 **dfdl:textNumberPattern for dfdl:textNumberRep
+\'standard\'**
+
+The dfdl:textNumberPattern property contains a positive and negative
+subpattern. Each subpattern has a prefix, a numeric part, and a suffix.
+If there is no explicit negative subpattern, the negative subpattern is
+the minus sign prefixed to the positive subpattern.
+
+It is a Schema Definition Error if any symbols other than \"0\", \"1\"
+through \"9\" or \# are used in the vpinteger region of the pattern.
+
+Significant digits may be used together with exponential notation. The
+\'@\' pattern character can be used only in \'standard\' textNumberRep
+(not \'zoned\') and excludes the \'P\' and \'V\' pattern characters. It
+is a Schema Definition Error if the \'@\' pattern character appears in
+\'zoned\' textNumberRep, or in conjunction with the \'P\' or \'V\'
+pattern characters.
+
+13.6.1.2 **dfdl:textNumberPattern for dfdl:textNumberRep \'zoned\'**
+
+When dfdl:textNumberRep is \'zoned\' a subset of the number pattern
+language is used. Only the pattern for positive numbers is used. It is a
+Schema Definition Error if the negative pattern is specified.
+
+A \'+\' may be present at the beginning or end of the pattern to
+indicate whether the leading or trailing digit carries the overpunched
+sign, if the logical type is unsigned. If logical type is unsigned and
+dfdl:textNumberPolicy \'lax\' specified it is a Schema Definition Error
+if no \'+\' is present.
+
+**13.8 Properties Specific to Float/Double with Binary
+Representation**
+
+The binaryFloatProperty specifies the encoding method for the float and
+double. Valid values are \'ieee\', \'ibm390Hex\'.
+
+For both \'ieee\' and \'ibm390hex\', an xs:float must have a physical
+length of 4 bytes. It is a Schema Definition Error if there is a
+specified length not equivalent to 4 bytes
+
+For both \'ieee\' and \'ibm390hex\', an xs:double must have a physical
+length of 8 bytes. It is a Schema Definition Error if there is a
+specified length not equivalent to 8 bytes.
+
+**13.9 Properties Specific to Boolean with Text Representation**
+
+The textBooleanTrueRep property contains a whitespace separated list of
+representations to be used for \'true\'. These are compared after
+trimming when parsing, and before padding when unparsing.
+
+If dfdl:lengthKind is \'explicit\' or \'implicit\' and either
+dfdl:textPadKind or dfdl:textTrimKind is \'none\' then both
+dfdl:textBooleanTrueRep and dfdl:textBooleanFalseRep must have the same
+length else it is a Schema Definition Error.
+
+_Text Boolean Character Restrictions:_ The string literal is restricted
+to allow only certain kinds of DFDL String Literal syntax:
+
+· DFDL character entities are allowed
+
+· The DFDL byte value entity ( %#rXX; ) is not allowed.
+
+· DFDL Character classes NL, WSP, WSP+, WSP\*, and ES are not
+allowed
+
+It is a Schema Definition Error if the string literal is the empty
+string or contains any of the disallowed constructs.
+
+The textBooleanFalseRep property contains a whitespace separated list of
+representations to be used for \'false\' These are compared after
+trimming when parsing, and before padding when unparsing.
+
+If dfdl:lengthKind is \'explicit\' or \'implicit\' and either
+dfdl:textPadKind or dfdl:textTrimKind is \'none\' then both
+dfdl:textBooleanTrueRep and dfdl:textBooleanFalseRep must have the same
+length else it is a Schema Definition Error.
+
+**13.10 Properties Specific to Boolean with Binary Representation**
+
+The binaryBooleanTrueRep property gives the representation to be used
+for \'true\'.
+
+The length of the data value of the element must be between 1 bit and 32
+bits (4 bytes) as described in Section 12.3.7.2. It is a Schema
+Definition Error if the value (when provided) of
+dfdl:binaryBooleanTrueRep cannot fit as an unsigned binary integer in
+the specified length.
+
+The binaryBooleanFalseRep property gives the representation to be used
+for \'false\'
+
+The length of the data value of the element must be between 1 bit and 32
+bits (4 bytes) as described in Section 12.3.7.2. It is a Schema
+Definition Error if the value of dfdl:binaryBooleanFalseRep cannot fit
+as an unsigned binary integer in the specified length.
+
+**13.11 Properties Specific to Calendar with Text or Binary
+Representation**
+
+The calendarLanguage property represents the language that is used when
+the pattern produces a presentation in text such as for names of the
+months, and names of days of the week.
+
+The value must match the regular expression:
+
+(\[A-Za-z\]{1,8}(\[\\-\_\]\[A-Za-z0-9\]{1,8})\*)
+
+It is a Schema Definition Error otherwise.
+
+**13.13 Properties Specific to Calendar with Binary Representation**
+
+The binaryCalendarRep property valid values are \'packed\', \'bcd\',
+\'ibm4690Packed\', \'binarySeconds\', \'binaryMilliseconds\' .
+
+For all these packed decimals, dfdl:calendarPattern can contain only
+characters and symbols that always result in the presentation of digits.
+It is a Schema Definition Error otherwise. This implies that property
+dfdl:calendarPatternKind must be \'explicit\' because the default
+patterns for \'implicit\' contain non-numeric characters. It is a Schema
+Definition Error otherwise.
+
+Note also that a virtual decimal point for the boundary between seconds
+and fractional seconds is implied from the pattern at the boundary of
+\'s\' and \'S\', i.e., where the substring \'sS\' appears in the
+pattern.
+
+· \'binarySeconds\' means represented as binary xs:int, that is,
+as a 4 byte signed integer that is the number of seconds from the epoch
+(positive or negative). It is a Schema Definition Error if there is a
+specified length not equivalent to 4 bytes.
+
+· \'binaryMilliseconds\' means represented as binary xs:long,
+that is, as an 8 byte signed integer that is the number of milliseconds
+from the epoch (positive or negative). It is a Schema Definition Error
+if there is a specified length not equivalent to 8 bytes.
+
+Values binarySeconds and binaryMilliseconds may only be used when the
+type is xs:dateTime. (It is a Schema Definition Error otherwise.)
+
+**13.16 Properties for Nillable Elements**
+
+The nilKind property specifies how dfdl:nilValue is interpreted to
+represent the nil value in the data stream.
+
+If \'literalCharacter\' then dfdl:nilValue specifies a single character
+or a single byte that, when repeated to the length of the element, is
+the nil value. \'literalCharacter\' may only be specified for
+fixed-length elements, otherwise it is a Schema Definition Error.
+
+Complex elements can be nillable, but dfdl:nilKind can only be
+\'literalValue\' and dfdl:nilValue must be \"%ES;\". It is a Schema
+Definition Error otherwise.
+
+The nilValue property specifies the text strings that are the possible
+literal or logical nil values of the element.
+
+Complex elements can be nillable, but dfdl:nilKind can only be
+\'literalValue\' and dfdl:nilValue must be \"%ES;\". It is a Schema
+Definition Error otherwise
+
+The nilValueDelimiterPolicy property enables distinguishing the nil
+representation from the representation of a value or an empty
+representation based on presence or absence of the initiator and
+terminator.
+
+The value of dfdl:nilValueDelimiterPolicy MUST only be checked if there
+is a dfdl:initiator or dfdl:terminator in scope. If so, and
+dfdl:nilValueDelimiterPolicy is not set, it is a Schema Definition
+Error. If dfdl:initiator is not \"\" and dfdl:terminator is \"\" and
+dfdl:nilValueDelimiterPolicy is \'terminator\' it is a Schema Definition
+Error. If dfdl:terminator is not \"\" and dfdl:initiator is \"" and
+dfdl:nilValueDelimiterPolicy is \'initiator\' it is a Schema Definition
+Error. It is not a Schema Definition Error if
+dfdl:nilValueDelimiterPolicy is \'both\' and one or both of
+dfdl:initiator and dfdl:terminator is \"\". This is to accommodate the
+common use of setting \'both\' as a schema-wide setting.
+
+It is a Schema Definition Error if dfdl:nilValueDelimiterPolicy is set
+to \'none\' or \'terminator\' when the parent xs:sequence has
+dfdl:initiatedContent \'yes\'.
+
+The useNilForDefault property ontrols whether to set the Infoset item
+**\[nilled\]** boolean member, or to use the XSD default or fixed
+properties to obtain a data value
+
+The dfdl:nilValue property must specify at least one nil value otherwise
+it is a Schema Definition Error.
+
+**14 Sequence Groups**
+
+The following properties are specific to sequences
+
+The sequenceKind property valid values are \'ordered\', \'unordered\'.
+When \'ordered\', this property means that the contained items of the
+sequence are expected in the same order that they appear in the schema,
+which is called schema-definition-order.
+
+When \'unordered\', this property means that the items of the sequence
+are expected in any order. Repeating occurrences of the same element do
+not need to be contiguous. The children of an unordered sequence must be
+xs:element otherwise it is a Schema Definition Error.
+
+The initiatedContent property vValid values are \'yes\', \'no\'. When
+\'yes\' indicates that all the children of the sequence are initiated.
+It is a Schema Definition Error if any children have their
+dfdl:initiator property set to the empty string.
+
+If the child is optional then it is known to exist when its initiator
+has been found. Any subsequent error parsing the child does not cause
+the parser to backtrack to try other alternatives.
+
+When \'no\', the children of the sequence may have their dfdl:initiator
+property set to the empty string.
+
+**14.1 Empty Sequences**
+
+A sequence having no children is syntactically legal in DFDL.
+
+It is a Processing Error if the SequenceContent region of an empty
+sequence has non-zero length when parsing.
+
+XML schema does not define an empty sequence that is the content model
+of a complex type definition as effective content so any DFDL
+annotations on such a construct would be ignored. It is a Schema
+Definition Error if the empty sequence is the content model of a complex
+type, or if a complex type has nothing in its content model at all.
+
+It is a Schema Definition Error if an empty sequence group appears as
+the model group of a complex type.
+
+**14.2 Sequence Groups with Separators**
+
+Additional properties apply to sequence groups that use text delimiters
+to separate one occurrence of a member of the group from the next.
+
+Sequence separator rules:
+
+1. A separator has alternative potential representations in the data.
+
+2. A separator is placed before, after, or between occurrences in the
+ data.
+
+3. Separators are used to indicate the position of occurrences in the
+ data
+
+These requirements are addressed by the properties dfdl:separator,
+dfdl:separatorPosition and dfdl:separatorSuppressionPolicy, as described
+below.
+
+These properties combine to define the syntax for a sequence group with
+dfdl:sequenceKind \'ordered\'. Not all combinations of the properties
+give rise to consistent syntax, so some combinations are disallowed and
+give rise to a Schema Definition Error.
+
+The separator property specifies a whitespace separated list of
+alternative DFDL String Literals that are the possible separators for
+the sequence.
+
+It is a Schema Definition Error if the expression returns an empty
+string.
+
+Each string literal in the list, whether apparent in the schema, or
+returned as the value of an expression, is restricted to allow only
+certain kinds of DFDL String Literal syntax:
+
+· DFDL character entities are allowed.
+
+· DFDL Byte Value entities ( %#rXX; ) are allowed.
+
+· DFDL Character Class ES is not allowed.
+
+· DFDL Character Classes NL, WSP, WSP+, and WSP\* are allowed.
+
+· The WSP\* entity cannot appear on its own as one of the string
+literals in the list when determining the length of a component by
+scanning for delimiters.
+
+If the above rules are not followed it is a Schema Definition Error.
+
+14.2.2 **Parsing Sequence Groups with Separators**
+
+When dfdl:occursCountKind is \'parsed\' any number of occurrences and
+their separators are expected. The dfdl:separatorSuppressionPolicy of
+the sequence must be \'anyEmpty\' and it is a Schema Definition Error
+otherwise.
+
+14.2.3 **Unparsing Sequence Groups with Separators**
+
+When dfdl:occursCountKind is \'parsed\' non zero-length occurrences in
+the augmented Infoset are output along with their separators. The
+dfdl:separatorSuppressionPolicy of the sequence must be \'anyEmpty\' and
+it is a Schema Definition Error otherwise.
+
+**14.3 Unordered Sequence Groups**
+
+14.3.1 ** \*\***Restrictions for Unordered Sequences\*\*
+
+t is a Schema Definition Error if any member of the unordered sequence
+is not an element declaration or an element reference.
+
+It is a Schema Definition Error if a member of an unordered sequence is
+an optional element or an array element and its dfdl:occursCountKind
+property is not \'parsed\'
+
+It is a Schema Definition Error if two or more members of the unordered
+sequence have the same name and the same namespace (see post-processing
+transformation below)
+
+It is a Schema Definition Error if an unordered sequence has no members.
+
+**14.4 Floating Elements**
+
+The floating property specifies whether the occurrences of an element in
+an ordered sequence can appear out-of-order in the representation. Valid
+values are \'yes\', \'no\'.
+
+It is a Schema Definition Error if an unordered sequence or a choice
+contains any element with dfdl:floating \'yes\'.
+
+It is a Schema Definition Error if an ordered sequence contains any
+element with dfdl:floating \'yes\' and also contains non-element
+component (such as a choice or sequence model group).
+
+It is a Schema Definition Error if an element with dfdl:floating \'yes\'
+is an optional element or an array element and its dfdl:occursCountKind
+property is not \'parsed\'
+
+It is a Schema Definition Error if two or more elements with
+dfdl:floating \'yes\' in the same group have the same name and the same
+namespace.
+
+**14.5 Hidden Groups**
+
+When the dfdl:hiddenGroupRef property is specified on an xs:sequence
+schema component, the appearance of any other DFDL properties on that
+component is a Schema Definition Error. It is also a Schema Definition
+Error if the sequence is not empty.
+
+It is a Schema Definition Error if the sequence is the only thing in the
+content model of a complex type definition.
+
+It is a Schema Definition Error if dfdl:hiddenGroupRef appears on a
+xs:group reference, that is, unlike most format properties that apply to
+sequences, dfdl:hiddenGroupRef cannot be combined from a xs:group
+reference.
+
+The hiddenGroupRef property is a reference to a global model group
+definition. Elements within this model group are not added to the
+Infoset and are called hidden elements.
+
+It is a Schema Definition Error if the value is the empty string.
+
+When unparsing a hidden group, the behaviour is the same as when
+elements are missing from the Infoset; that is, the default-values
+algorithm applies. The only difference is that if a required element
+does not have a default value or a dfdl:outputValueCalc then it is a
+Schema Definition Error instead of a Processing Error. Note that this
+can be checked statically.
+
+When unparsing a hidden group, it is a Processing Error if an element
+information item is provided in the Infoset for a hidden element.
+
+**15 Choice Groups**
+
+A choice corresponds to concepts variously called variant records,
+multi-format records, discriminated unions, or tagged unions in various
+programming languages.
+
+The Root of the Branch must not be optional. That is XSD minOccurs must
+be greater than zero.
+
+A choice that declares no branches in the DFDL schema is a Schema
+Definition Error.
+
+When processing a choice group, the parser validates any contained path
+expressions. If a path expression contained inside a choice branch
+refers to any other branch of the choice, then it is a Schema Definition
+Error. Note that this rule handles nested choices also. A path that
+navigates outward from an inner choice to another alternative of an
+outer choice is violating this rule with respect to the outer choice.
+
+The initiatedContent property indicates whether all the branches of the
+choice are initiated. Valid values are \'yes\', \'no\'.
+
+When \'yes\' indicates that all the branches of the choice are
+initiated. It is a Schema Definition Error if any children have their
+dfdl:initiator property set to the empty string.
+
+The choiceDispatchKey property string must match one of the
+dfdl:choiceBranchKey property values of one of the branches of the
+choice.
+
+The expression must evaluate to an xs:string. It is a Schema Definition
+Error if the expression returns an empty string.
+
+It is a Schema Definition Error if the expression contains forward
+references to elements which have not yet been processed.
+
+It is a Processing Error if the value of the expression does not match
+any of the dfdl:choiceBranchKey property values for any of the branches.
+
+It is a Schema Definition Error if any choice branch does not specify a
+dfdl:choiceBranchKey in a choice that carries choiceDispatchKey.
+
+The choiceBranchKey property provides an alternate way to discriminate a
+choice to a branch.
+
+It is a Schema Definition Error if individual dfdl:choiceBranchKey
+values are not unique across all branches of a choice that carries
+dfdl:choiceDispatchKey.
+
+It is a Schema Definition Error if dfdl:choiceBranchKey is specified on
+a global element, or on a sequence or choice that is the child of a
+global group definition.
+
+It is a Schema Definition Error if any choice branch does not specify a
+dfdl:choiceBranchKey in a choice that carries choiceDispatchKey.
+
+15.1.2 **Resolving Choices via Direct Dispatch**
+
+Direct dispatch provides a constant-time dispatch to a choice branch
+independent of how many choice branches there are.
+
+Direct dispatch is indicated by the dfdl:choiceDispatchKey property.
+
+The dfdl:choiceBranchKey property can be placed on element references,
+local element declarations, local sequences, local choices, or group
+references. All values of dfdl:choiceBranchKey properties must be unique
+across all branches of a choice that carries a dfdl:choiceDispatchKey
+property and it is a Schema Definition Error otherwise.
+
+Note that it is a Schema Definition Error if both dfdl:initiatedContent
+and dfdl:choiceDispatchKey are provided on the same choice. However, it
+is not an error if a discriminator exists on a choice branch along with
+a dfdl:choiceBranchKey.
+
+15.1.3.1 **Unparsing Choices in Hidden Groups**
+
+When a choice appears inside a hidden group, there are no corresponding
+Infoset elements as there are none for hidden groups. The first branch
+of the choice is unparsed. All elements contained in the branch must
+have default values or must have dfdl:outputValueCalc properties to
+compute their values, and it is a Schema Definition Error otherwise.
+
+**16.1 The** **dfdl:occursCountKind property**
+
+16.1.1 **dfdl:occursCountKind \'fixed\'**
+
+It is a Schema Definition Error if XSD minOccurs is not equal to XSD
+maxOccurs.
+
+16.1.4 **dfdl:occursCountKind \'expression\'**
+
+It is a Schema Definition Error if dfdl:occursCount is not provided or
+in scope.
+
+16.1.5 **dfdl:occursCountKind \'stopValue\'**
+
+It is a Schema Definition Error if dfdl:occursStopValue is not provided
+or in scope.
+
+It is a Schema Definition Error if the type of the element is complex.
+
+It is a Schema Definition Error if any of the stop values provided by
+dfdl:occursStopValue do not conform to the simple type of the element.
+
+
+
+**17 Calculated Value Properties**
+
+The inputValueCalc property contains an expression that calculates the
+value of the element when parsing.
+
+It is a Schema Definition Error if the result type of the expression
+does not conform to the base type of the element.
+
+It is a Schema Definition Error if this property is specified on an
+element which has an XSD fixed or default property.
+
+It is a Schema Definition Error if dfdl:inputValueCalc and
+dfdl:outputValueCalc are specified on the same element.
+
+If this property appears on an element declaration or element reference
+schema component, the appearance of any other DFDL properties on that
+component is a Schema Definition Error.
+
+The outputValueCalc property is an expression that calculates the value
+of the current element when unparsing.
+
+It is a Schema Definition Error if the result type of the expression
+does not conform to the base type of the element.
+
+It is a Schema Definition Error if dfdl:outputValueCalc is specified on
+an element which has an XSD fixed or default property.
+
+It is a Schema Definition Error if dfdl:inputValueCalc and
+dfdl:outputValueCalc are specified on the same element.
+
+18.2.2 **Variable Memory State Transitions**
+
+It is a Schema Definition Error if a dfdl:setVariable or a variable
+reference occurs and there is no corresponding variable name defined by
+a dfdl:defineVariable annotation.
+
+It is a Schema Definition Error if a dfdl:setVariable provides a value
+of incorrect type which does not correspond to the type specified by the
+dfdl:defineVariable.
+
+It is a Schema Definition Error if a variable reference in an expression
+is able to return a value of incorrect type for the evaluation of that
+expression. That is, DFDL - including the expressions contained in it -
+is a statically type-checkable language. DFDL implementations SHOULD
+issue these Schema Definition Errors prior to processing time if
+possible.
+
+**18.3 General Syntax**
+
+DFDL expressions follow the XPath 2.0 syntax rules but are always
+enclosed in curly braces \"{\" and \"}\".
+
+The syntax \"{}\" is a Schema Definition Error as it results in an empty
+XPath 2.0 expression which is not legal.
+
+The result of evaluating the expression must be a single atomic value of
+the type expected by the context, and it is a Schema Definition Error
+otherwise. Some XPath expressions naturally return a sequence of values,
+and in this case, it is also Schema Definition Error if an expression
+returns a sequence containing more than one item.
+
+**18.4 DFDL Expression Syntax**
+
+Predicates are only used to index arrays and so must be integer
+expressions otherwise a Schema Definition Error occurs.
+
+**18.5 Constructors, Functions and Operators**
+
+The arguments to the constructors are all of type xs:anyAtomicType.
+Since the expression language can be statically type checked, it is a
+Schema Definition Error if the type of the argument is not one of the
+DFDL-supported subtypes of xs:anyAtomicType.
+
+If the argument for the function below includes the current node, or any
+enclosing parent node, then it is a Schema Definition Error.
+
+fn:empty(\$arg?)
+
+fn:exists(\$arg?)
+
+fn:exactly‑one(\$arg?)
+
+fn:count(\$arg)
+
+18.5.3 **DFDL Functions**
+
+dfdl:contentLength(\$node, \$lengthUnits)
+
+The second argument is of type xs:string and must be \'bytes\',
+\'characters\', or \'bits\', otherwise it is a Schema Definition Error.
+
+dfdl:valueLength(\$node, \$lengthUnits)
+
+The second argument is of type xs:string and must be \'bytes\',
+\'characters\', or \'bits\', otherwise it is a Schema Definition Error.
+
+dfdl:occursIndex()
+
+It is a Schema Definition Error if this function is called when there is
+no enclosing array element.
+
+dfdl:checkConstraints(\$node)
+
+It is a Schema Definition Error if the argument is a complex element.
+
+dfdl:decodeDFDLEntities (\$arg)
+
+t is a Schema Definition Error if \$arg contains syntax matching DFDL
+Byte Value Entities syntax.
+
+dfdl:checkRangeInclusive(\$node, \$val1, \$val2)\
+dfdl:checkRangeExclusive(\$node, \$val1, \$val2)
+
+The type of \$val1 and \$val2 must be compatible with the type of
+\$node, and must be a derivative of xs:decimal, xs:float or xs:double.
+It is a Schema Definition Error if the \$node argument is a complex
+element.
+
+dfdl:byte (\$arg)
+
+dfdl:unsignedByte (\$arg)
+
+dfdl:short (\$arg)
+
+dfdl:unsignedShort(\$arg)
+
+dfdl:int (\$arg)
+
+dfdl:unsignedInt (\$arg)
+
+dfdl:long (\$arg)
+
+dfdl:unsignedLong (\$arg)
+
+If the string begins with \'x\', it is a Schema Definition Error if a
+character appears other 0-9, a-f, A-F.
+
+Each constructor function has a limit on the number of hex digits, with
+no more digits than 2, 4, 8, or 16 for the byte, short, int and long
+versions respectively. It is a Schema Definition Error if more digits
+are encountered than are suitable for the type being created.
+
+dfdl:hexBinary (\$arg)
+
+If a literal number is not able to be represented by a long, it is a
+Schema Definition Error.
+
+Table 67: DFDL Constructor Functions
+
+Expression deadlocks are always Schema Definition Errors
+
+**19 DFDL Regular Expressions**
+
+The following regular expression constructs are not common to both ICU
+and Java(R) 7 and it is a Schema Definition Error if any are used in a
+DFDL regular expression:
+
+\\N{UNICODE CHARACTER NAME}
+
+\\X
+
+\\Uhhhhhhhh
+
+(?# \... )
+
+(?w-w)
+
+(?d-d)
+
+(?u-u)
+
+(?U-U)
+
+**23 Optional DFDL Features**
+
+It is a Schema Definition Error if a DFDL schema uses an optional
+feature that is not supported by a minimal or extended conforming
+processor.
