Matt Nolan posed a question to the panel that'd been hanging in the air since the first day of the Virtual Globes conference : What do data exchange formats look like for 3d globes? Hard core open source GIS users and standards advocates would immediately say OGC's GML. The popular wave, on the other hand, which has really enlightened people to the usefulness of geospatial data would back KML as a de facto universal standard.

My answer went something like this (although this entry's probably clearer): The analogy and history of HTML is probably quite instructive. Before HTML, prior to 1993/1994, there was this beautiful trainwreck called SGML that was used for document "exchange." HTML was widely adopted as a document markup language to the chagrin and much gnashing of teeth from the SGML crowd, but without HTML, there would've been no web or internet as the masses know it. Sorry, but gopher and wais do not Al Gore's internet make. Then, mutations happened. Netscape came along and introduced blasphemy: the IMG tag. Where would the web be without images? That didn't come from TBL. Microsoft, not to be outdone, introduced their "innovation:" the blink tag. Some mutations are good for evolution, some lead down a null path. C'est la innovation.

By 1998, the SGML crowd had not gone quietly into that good night and fought back with XML. Back then, I recall the years 1993 - 1998 to be eons. Crazy things were happening then that started with the word "Dot" and eventually ended with the word "Boom." Looking at it, that's a scant 5 years. Five years later, SGML had gone more or less by the wayside and we had a robust HTML 4 standard and XML, daddy of WebServices, SOA, and AJAX.

Geospatial interop? My prediction is by 2007, KML will be even more different than the neatness that's in KML 2.0 and probably a GML profile, while GML, itself, will also be something different.

So, if you're new to GML 3.1.1, take my advice from my experience with SGML & HTML - Learning EBNF might be fun for parties, but ya' ain't gonna use it - learn KML inside and out and why it needs to grow.