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Subject: DTD in PDF?
The question arose in discussion of the ACXO, does the present spec allow one to describe a DTD that is presented in PDF? The answer is yes from data-element.dtd: <!ELEMENT representation ( representation-label, datatype-label?, format?, character-set-name?, unit-of-quantity? )> <!ELEMENT representation-label (#PCDATA)> <!ATTLIST representation-label xsgml-type (%xsgml-entity-list;) #IMPLIED > ... <!ELEMENT format EMPTY> <!ATTLIST format mime-type (%mime-type-list;) #REQUIRED > as used in db1.txt: <representation> <representation-label xsgml-type="sgml-dtd"/> </representation> which is therefore an incomplete example. I didn't provide a text string as content of representation-label because I figured it could be autogenerated. But, as Ron Schuldt pointed out, plain text is only one format for a DTD; it could also be presented in PDF or HTML. So I should have added a format element, <format mime-type="text/plain"/> for the db1.txt example, and for the same presented in PDF it would be <format mime-type="application/PDF"/> I append the relevant documentation (from rrdtddoc.hrm, slightly maimed by having been cut-and-pasted from HTML): representation Part 1, definition 3.3.60: “the combination of a value domain, datatype, and, if necessary, a unit of measure or a character set.” Part 1, definition 3.3.61:: “type of symbol, character or other designation used to represent a data element.” For example, a DTD may be supplied in text or PDF. ISO/IEC 11179 supplies more content for this element than seems needed for registering DTDs and schemas, but it has been retained anyway: a label, a label for a datatype, a description of format, a name for character set, and a unit of quantity. representation-label in ISO/IEC 11179, “representation term”, here renamed for consistency and employed a bit loosely; Part 1, definition 3.3.62: “a component of a data element name which describes the form of representation of the data element.” Its content is a string and the value of its xsgml-type attribute is drawn from xsgml-entity-list.ent. This element indicates whether a registered entity is a DTD, a schema, general text, and so forth. datatype-label a string indicating the datatype of the data element or data element dictionary; possibly overlapping with representation-label. Part 1, definition 3.3.25, for “datatype”: “the format used for the collection of letters, digits, and/or symbols, to depict values of a data element, determined by the operations that may be performed on the data element.” format an empty element, indicating through its mime-type attribute the MIME type of the registered entity. character-set-name a string naming the character set of a registered entity. unit-of-quantity a string naming the unit of quantity used for values of a data element; not relevant to registration of DTDs and schemas. regards, Terry
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