The continued evolution of the Web will engender applications requiring increasingly more sophisticated data formats. To supply the extensibility, structure, and validation needed by future Web publishers, the World Wide Web Consortium has developed XML, a standardized data format that goes beyond the current generation of HTML tools to meet the needs of large-scale content providers.
The same qualities that make XML useful in the future of Web publishing also make it well suited to the data requirements of present-day scientific and medical applications. In particular, XML's ability to express arbitrarily deep hierarchical data structures make it an excellent choice for applications in which the data are intended to drive object-oriented downstream processes.
Chemical Markup Language is a paradigmatic example of such an application. CML standardizes a particular XML format that allows researchers the world over to capture chemical data in a form that can be reused not just with the Java programs that constitute the typical processing environment in its first release but also with future processes as yet undefined. This groundbreaking use of XML will set the standard for a large number of similar applications that will appear over the next serveral years.