Non-normative information

In this section:

1. About the specification source
   The DITA specification is authored in DITA. It is a complex document that uses many DITA features, including key references (keyrefs), content references (conrefs), and controlled values set in a subject scheme map.
2. Changes from previous versions
   The following topics outline the changes from earlier versions of DITA to the current version. Each version of the DITA specification is designed to be backwards-compatible with applications that conform to earlier versions of the DITA specification.
3. File naming conventions
   The DITA OASIS Technical Committee uses certain conventions for the names of XML grammar files. We suggest using these conventions as a best practice to facilitate interchange of grammar files.
4. Migrating to new versions of DITA
   DITA 1.3 is compatible with prior versions of the DITA specification; all valid DITA 1.0, 1.1, and 1.2 documents are valid DITA 1.3 documents. However, some changes to existing document-type shells and specializations might be needed in order to maintain the same behavior under DITA 1.3 or to take full advantage of new DITA 1.3 features.
5. Considerations for generalizing <foreign> elements
   The <foreign> element can contain a mixture of DITA and non-DITA content. Non-DITA content that is contained within a <foreign> element cannot be generalized. However, the <foreign> element itself, as well as any DITA elements that it contains, can be generalized using normal rules.
6. Element-by-element recommendations for translators: All-inclusive edition
   This topic contains a list of all OASIS DITA elements that are available in the edition. It includes recommendations on how to present the element type to translators, whether the element contents are likely to be suitable for translation, and whether the element has attributes whose values are likely to be suitable for translation. Examples of content that is not suitable for translation include code fragments and mailing addresses.
7. DTD public identifiers
   Each document-type shell (.dtd file) or module component (.mod or .ent file) has a public identifier. The public identifier can reference either the latest version or a specific version of the document-type shell or module component.
8. XML Schema catalog identifiers
   Each Schema document must be uniquely identified using a Uniform Resource Name (URN). Each Schema document has a version-independent as well as a version-specific URN.
9. Domains and constraints in the OASIS specification
   This section provides a summary of the domains and constraints that are available as part of the OASIS specification, as well as a summary of how they are used.
10. Processing interoperability considerations
    The DITA specification does not require processors to perform filtering, content reference resolution, key space construction, and other processing related to base DITA semantics in any particular order. This means that different conforming DITA processors might produce different results for the same initial data set and filtering conditions. DITA users and DITA implementers need to be aware of these potential differences in behavior when DITA content will be processed by different processors.
11. Specialization design, customization, and the limits of specialization
    DITA specialization imposes certain restrictions. An inherent challenge in designing DITA vocabulary modules and document types is understanding how to satisfy markup requirements within those restrictions and, when the requirements cannot be met by a design that fully conforms to the DITA architecture, how to create customized document types that diverge from the DITA standard as little as possible.