Example: Constrain attributes for the <section> element using
DTD
This section is non-normative.
In this scenario, a DITA architect wants to
redefine the attributes for the <section>
element. They want to make the @id
attribute required.
Example
This section is non-normative.
- The DITA architect creates a constraint module: idRequiredSectionContraint.mod.
- They add the following content to
idRequiredSectionContraint.mod:
<!-- Declares the entities referenced in the constrained content --> <!-- model. --> <!ENTITY % localization-atts "translate (no | yes | -dita-use-conref-target) #IMPLIED xml:lang CDATA #IMPLIED dir (lro | ltr | rlo | rtl | -dita-use-conref-target) #IMPLIED" > <!ENTITY % filter-atts "props CDATA #IMPLIED %props-attribute-extensions;" > <!ENTITY % select-atts "%filter-atts; base CDATA #IMPLIED %base-attribute-extensions; importance (default | deprecated | high | low | normal | obsolete | optional | recommended | required | urgent | -dita-use-conref-target) #IMPLIED rev CDATA #IMPLIED status (changed | deleted | new | unchanged | -dita-use-conref-target) #IMPLIED" > <!ENTITY % conref-atts "conref CDATA #IMPLIED conrefend CDATA #IMPLIED conaction (mark | pushafter | pushbefore | pushreplace | -dita-use-conref-target) #IMPLIED conkeyref CDATA #IMPLIED" > <!-- Redefines the attributes available on section --> <!ENTITY % section.attributes "id ID #REQUIRED %conref-atts; %select-atts; %localization-atts; outputclass CDATA #IMPLIED" >Note that the DITA architect had to declare all the parameter entities that are referenced in the redefined attributes for
<section>. If they did not do so, none of the attributes that are declared in the parameter entities would be available on the<section>element. Furthermore, since the%select-atts;parameter entity references the%filter-atts;parameter entity, the%filter-atts;must be declared and it must precede the declaration for the%select-atts;parameter entity. The%props-attribute-extensions;and%base-attribute-extensions;parameter entities do not need to be declared in the constraint module, because they are declared in the document-type shells before the inclusion of the constraint module. - They add the constraint module to the catalog.xml file.
- They then integrate the constraint module
into the applicable document-type shells by
adding the following
code:
<!-- ============================================================= --> <!-- ELEMENT-TYPE CONFIGURATION INTEGRATION --> <!-- ============================================================= --> <!ENTITY % section-constraints-c-def PUBLIC "-//ACME//ELEMENTS DITA 2.0 Section Constraint//EN" "idRequiredSectionContraint.mod"> %section-constraints-c-def; - They check their test topic to ensure that the attribute list is modified as expected.