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.
The public identifiers for the DTD files that are maintained by OASIS use the following format:
"-//OASIS//DTD DITA version information-type//EN"
Note that "OASIS" is the owner identifier; this indicates that the artifacts are owned by OASIS. The keyword "DITA" is a convention that indicates that the artifact is DITA-related.