dfdl:group and dfdl:choice are used as "attribute form" annotations to
xs:group and xs:choice respectively. For example:
<xs:group name="foo">
<xs:annotation>
<xs:appinfo source="http://www.ogf.org/dfdl/";>
<dfdl:group encoding="UTF-8" ... />
</xs:appinfo>
</xs:annotation>
...
</xs:group>
Note that the dfdl: prefix isn't need on the encoding property because
it is on the dfdl:group element.
The above is equivalent to using "short form" annotations like below,
which is the most common form since it is so much less verbose:
<xs:group name="foo" dfdl:encoding="UTF-8" ... />
...
</xs:group>
Note that the dfdl: prefix is needed here because it is on the xs:group
element.
There is also a third form called "element form" which looks like this:
<xs:group name="foo">
<xs:annotation>
<xs:appinfo source="http://www.ogf.org/dfdl/";>
<dfdl:group>
<dfdl:property name="encoding">UTF-8"</dfdl:property>
</dfdl:group>
</xs:appinfo>
</xs:annotation>
...
</xs:group>
So instead of being attributes on the xs:group or the dfdl:group
annotation, it appears as a dfdl:propery element that is a child of the
dfdl:group element.
Each property in the spec lists the annotations it can appear on. For
example, the "encoding" property lists these:
Annotation: dfdl:element, dfdl:simpleType, dfdl:sequence, dfdl:choice,
dfdl:group
So the "encoding" property can appear on any of those 5 annotations
using any of the three property binding forms.
Section 7.1 of the spec lists the different annotations
https://daffodil.apache.org/docs/dfdl/#_Toc62570077
Note that it isn't specific to groups or choices--elements, sequences,
simleTypes, etc, have similar annotations.
On 2023-04-26 11:01 AM, Regis Thomas wrote:
Good Morning Daffodil/DFDL Users,
I am working on the development of intellisense for dfdl in the Apache
Daffodil VSCode extension. As we prepare to release version 1.3.0. I am
scouring through the Apache DFDL spec
https://daffodil.apache.org/docs/dfdl/
<https://daffodil.apache.org/docs/dfdl/> for any items that I have
missed implementing in the 1.3.0 release to add to the 1.3.1 release. I
noticed that I was missing the dfdl:choice and dfdl:group elements in
the intellisense. From the spec, I don’t understand what element(s)
might be parents of these elements. I also don’t understand what
element might be children of these elements or what attributes they
might have. Usually I have been able to find examples of an element’s
use that helped clarify how I might add that element to the
intellisense, but I haven’t been able to find any examples of either
dfdl:choice or dfdl:group in use. If anyone could provide an example or
additional clarification, that would be greatly appreciated.
Regis Thomas
Nteligen, LLC
6716 Alexander Bell Drive,
Suite 120
Columbia, MD 20146
(240) 864-5042 x126
regis.tho...@nteligen.com
