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The presented specification allows legacy systems that may presently be unable to convert their DTD markup declarations to XML Schema, to utilize XML Schema conformant datatypes. With it, DTD creators can specify datatypes for attribute values and data content, thereby providing the foundation for a smoother future transition path.
NOTE: Free open-source code that supports this specification for both SAX and DOM is available at www.extensibility.com/dt4dtd.
A datatype declaration is a fixed attribute named "a-dtype" or "e-dtype". The fixed, "a-dtype" default value must consist of a series of name/value pairs according to the following syntax:
The fixed, e-dtype default value must consist merely of a name.
For example:
<!ATTLIST person
birthdate CDATA #IMPLIED
height CDATA #IMPLIED
e-dtype CDATA #FIXED
"social-security-number"
a-dtype CDATA #FIXED
"pubdate date
binding length">
The attrNames are the names of attributes declared in the same attribute-list declaration for the element type. The dtypeName that follows is associated with the attribute of that name.
The e-dtype attribute can only be declared if the associated element type's content allows data but no sub-elements. The dtypeName is associated with the data content of elements of that type.
NOTE: The "dtype" attributes are based on notations instead of XML Namespaces because they are meaningful in the DTD and not in the document instance. It must be possible for DTD-reading and writing applications to recognize the attributes in an entity containing DTD declarations without parsing a document for namespace declarations. The set of namespace declarations that apply to an element type can vary according to context and cannot in general be recognized in a DTD.
A dtypeName must be the name of a notation declared in the DTD; the notation declaration must include a system identifier that is a URI reference. However, if the datatype's name is somehow known to the information system because of the processing context, these notation declarations may be omitted. Notation declarations for datatypes native to the W3C XML Schema specifiation may always be omitted; every information system must natively recognize them from their dtypeName.
When explicit notations are provided for dtypeNames, their associated system URIs must refer to one of the following.
The referent of the associated URI reference may be an XML Schema datatypeDefn. If so, a conforming processor may validate the attribute value or data content according to that specification.
The referent of the associated URI may be XML-Data datatypes as defined by these declarations, which may be included directly or through an entity reference.
<!NOTATION string SYSTEM "urn:schemas-microsoft-com:datatypes/string"> <!NOTATION number SYSTEM "urn:schemas-microsoft-com:datatypes/number"> <!NOTATION int SYSTEM "urn:schemas-microsoft-com:datatypes/int"> <!NOTATION float SYSTEM "urn:schemas-microsoft-com:datatypes/float"> <!NOTATION fixed.14.4 SYSTEM "urn:schemas-microsoft-com:datatypes/fixed.14.4"> <!NOTATION boolean SYSTEM "urn:schemas-microsoft-com:datatypes/boolean"> <!NOTATION dateTime.iso8601 SYSTEM "urn:schemas-microsoft-com:datatypes/date.type.iso8601"> <!NOTATION dateTime.iso8601tz SYSTEM "urn:schemas-microsoft-com:datatypes/dateTime.iso8601tz"> <!NOTATION date.iso8601 SYSTEM "urn:schemas-microsoft-com:datatypes/date.iso8601"> <!NOTATION time.iso8601 SYSTEM "urn:schemas-microsoft-com:datatypes/time.iso8601"> <!NOTATION time.iso8601.tz SYSTEM "urn:schemas-microsoft-com:datatypes/time.iso8601.tz"> <!NOTATION i1 SYSTEM "urn:schemas-microsoft-com:datatypes/i1"> <!NOTATION i2 SYSTEM "urn:schemas-microsoft-com:datatypes/i2"> <!NOTATION i4 SYSTEM "urn:schemas-microsoft-com:datatypes/i4"> <!NOTATION i8 SYSTEM "urn:schemas-microsoft-com:datatypes/i8"> <!NOTATION ui1 SYSTEM "urn:schemas-microsoft-com:datatypes/ui1"> <!NOTATION ui2 SYSTEM "urn:schemas-microsoft-com:datatypes/ui2"> <!NOTATION ui4 SYSTEM "urn:schemas-microsoft-com:datatypes/ui4"> <!NOTATION ui8 SYSTEM "urn:schemas-microsoft-com:datatypes/ui8"> <!NOTATION r4 SYSTEM "urn:schemas-microsoft-com:datatypes/r4"> <!NOTATION r8 SYSTEM "urn:schemas-microsoft-com:datatypes/r8"> <!NOTATION float.IEEE.754.32 SYSTEM "urn:schemas-microsoft-com:datatypes/float.IEEE.754.32"> <!NOTATION float.IEEE.754.64 SYSTEM "urn:schemas-microsoft-com:datatypes/float.IEEE.754.64"> <!NOTATION uuid SYSTEM "urn:schemas-microsoft-com:datatypes/uuid"> <!NOTATION uri SYSTEM "urn:schemas-microsoft-com:datatypes/uri"> <!NOTATION bin.hex SYSTEM "urn:schemas-microsoft-com:datatypes/bin.hex"> <!NOTATION char SYSTEM "urn:schemas-microsoft-com:datatypes/char"> <!NOTATION string.ansi SYSTEM "urn:schemas-microsoft-com:datatypes/strin.ansi">
The referent of the associated URI may be some other notation established for use within some processing context. Optionally, such referents may be Java classes, XSL stylesheets, et. al. that are able to programatically test for validity.
This specification has certain optional features intended to support an existing installed base and also to allow customization of the specification for closed information systems. This section defines a subset called the "Strict Conformance Subset" that should be used for blind (not pre-arranged) information interchange on the World Wide Web.
A DTD that conforms to the strict subset will have a notation declaration for every dtypeName used in a datatype declaration except datatypes declared in the W3C XML Schema specification. It will aslo have a single explicit conformance declaration.
The conformance declaration must only be used in DTDs that otherwise conform to the strict subset. This declaration is a notation declaration with the URI "http://www.w3.org/TR/1999/dt4dtd".
If present, the conformance notation declaration must precede the first attribute list declaration in a set of DTD declarations. For the convenience of human readers, we suggest that the conformance notation be named "dt4dtd".
NOTE: The principle of Information Set Contributions is established in the W3C XML Schema specification.
In an information set supporting this specification: