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dtd-version Version of the Tag Set (DTD)

Version of the BITS Tag Set to which this document claims to be valid.

Usage/Remarks

Best Practice

This attribute should be set on every document instance explicitly, even when using the XSD or RNG version of BITS.
Historical Note
Until Version 1.3 of JATS, @dtd-version was a #FIXED attribute, set in the schema/DTD, that could not be changed by the JATS user. It was intended to name the highest-level version of JATS to which the document was valid. Being #FIXED meant that the attribute was always there, even if it was not present in the document. BITS followed JATS in this practice, and @dtd-version was a #FIXED attribute.
Having a set version number was convenient for some applications, but inconvenient for others, particularly for repositories that house BITS documents of different versions at the same time, most of which may be valid to more than one version of BITS.
The @dtd-version attribute has never provided a complete description of which version of the tag set a document is associated with, since it did not provide information such as which table model(s), which MathML version, etc. were used. Therefore several attributes were added to the <processing-meta> element to describe the tag set version choices more fully:
OPTIONAL on elements: <book>, <book-part-wrapper>
Value Meaning
1.0 Version 1.0 of BITS
2.0 Version 2.0 of BITS
2.1 Version 2.1 of BITS
Restriction @dtd-version is an optional, recommended attribute; there is no default.
Tagged Sample

Designating BITS’ current version (2.1) as the validating schema

<book
  xmlns:mml="http://www.w3.org/1998/Math/MathML"
  xmlns:xi="http://www.w3.org/2001/XInclude"
  xmlns:xlink="http://www.w3.org/1999/xlink"
  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  book-type="gov"
  dtd-version="2.1"
  indexed="yes"
  xml:lang="en">
 <book-meta>...</book-meta>
 <book-body>...</book-body>
 <book-back>...</book-back>
</book>