OK, let's bite the bullet:
OLD
The "path" statement, which is a substatement to the "type"
statement, MUST be present if the type is "leafref". It takes as an
argument a string that MUST refer to a leaf or leaf-list node.
The syntax for a path argument is a subset of the XPath abbreviated
syntax. Predicates are used only for constraining the values for the
key nodes for list entries. Each predicate consists of exactly one
equality test per key, and multiple adjacent predicates MAY be
present if a list has multiple keys. The syntax is formally defined
by the rule "path-arg" in Section 14.
NEW
The "path" statement, which is a substatement to the "type"
statement, MUST be present if the type is "leafref". The syntax for
its argument is formally defined by the rule "path-arg" in
Section 14.
The "path" statement is used in two ways:
1. It refers to another "leaf" node that is obtained by treating the
"path" argument as a path in the schema tree. If the argument
begins with the slash character ("/"), i.e., corresponds to the
ABNF rule "absolute-path", the path starts at the root of the
schema tree, otherwise it starts at the current "leaf" node with
the "leafref" type.
The steps along this path are performed by interpreting each
of the slash-separated components of the "path" argument as
follows:
o If the component is the double-dot string (".."), go to the
closest schema tree ancestor that is a data node or schema root.
o Otherwise, the component contains a data node identifier and an
optional path predicate enclosed in square brackets. Go to the
data child (see below) whose name is the data node identifier.
A data child of data node N is a descendant node in the schema
tree for which node N is the closest ancestor that is a data
node.
The path predicate, if present, is ignored.
The "leaf" node to which the "path" argument refers MUST exist in
the schema tree.
2. If the "require-instance" property (Section 9.9.3) is "true", the
"path" argument is evaluated as an XPath expression once for each
instance of the "leaf" with the "leafref" type. The result of
every such evaluation MUST be a non-empty node set.
Path predicates are used only for specifying the values for the
key nodes for list entries. Each predicate consists of exactly one
equality test per key, and multiple adjacent predicates MAY be
present if a list has multiple keys.
Lada
--
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C
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