Semantic extensions to domain-specific markup languages

A markup language serves as a medium of communication for storing and publishing textual, numeric and other forms of data seamlessly. XML, the eXtensible Markup Language has become the lingua franca in web publishing. It is also a widely accepted standard for databases and document storage. There are many domain-specific markup languages designed using special XML tag sets. Standardization bodies and research communities may extend these to include additional semantics of areas within and related to the domain. This paper outlines the issues to be considered when extending domain-specific markup languages, namely, the motivation for extension, the semantic considerations, the syntactic constraints and other relevant aspects. Illustrating examples are given from the domains of Medicine, Finance and Materials Science. Particular emphasis in these examples is on the extension of the Materials Science Markup Language MatML to include the semantics of one sub-area, namely, the Heat Treating of Materials. The focus of this paper however is not the design of one particular language but rather the generic issues involved in extending domain-specific markup languages.