dtd-version Version of the Tag Set (DTD)
Version of the NISO STS Tag Set that should be used to validate this standards document.
This attribute should be set on every document instance explicitly, even when using the XSD or RNG version of NISO STS. This is a “fixed” attribute (meaning that the value is set via a parameter entity in the DTD; thus, an author or editor cannot change it). To keep with the latest DTD, the value should be changed every time the NISO STS Tag Set changes its version number.