ComicsML is a markup language designed to more easily describe strip comics such as daily newpaper comics or webcomics. It's similar to CBML, except that the latter has no concept of single strips and lacks some other features commonly found in webcomics.
ComicsML was originally created by Jason McIntosh (who wrote an essay at XML.com) and has had some software written for it, including Renoberator (in Java). However, the standard hasn't seen any active use or development for several years and never progressed beyond version 0.2.
When Metrophor was conceived, I knew that I wanted to do it properly: with searchable archives based on characters, dialog, in-story location, and other metadata. ComicsML seemed to be a perfect solution to the problem I had devised for myself. In addition to having metadata for each comic that could be searched by visitors, having an XML document would assist in layout and collaboration: since Metrophor is designed by two people, one author and one artist, having a common language could make things much simpler than emails flying between us saying "no, try putting that one thing over here instead. No, now try moving that balloon into the other panel."
After getting permission from Jason to go forward with the project, I began to work on updating the XML DTD. It's now reached its first post-Jason version, and comments are being sought. It's substantially different from the 0.2 version, although it's a priority to retain some backwards compatibility. If you wish to comment on the new version (please do!) or give some ideas for other elements to be included (please do!), then please visit the forum. Help and other suggestions are, of course, also welcome.