GeoPDF is, always has been, and always will be PDF. It has its roots in publishing utility drawings in different to utilities operations and maintenance field workers to PDF file sets augmented with feature data and convenient navigational features derived from different databases and other data stores. In order to place things like hyperlinks to detail drawings on a map, we had to derive the relationship between the real world location of some item of plant and the corresponding location on the PDF page.
Once this association can be made, it's relatively straight forward to generalize it. There a bunch of ways to skin that cat, we chose a georegistration technique that relates the PDF coordinate system to a projected coordinate system similar to the way it's done in GeoTIFF. Just as GeoTIFF uses TIFF constructs to embed georegistration metadata, GeoPDF uses PDF constructs to embed georegistration metadata. Emacs and a GeoPDF file reveals all. Just as GeoTIFF *is* TIFF, GeoPDF *is* PDF.
Our georegistration technique was designed for internal use and compatibility with internally-developed tools and libraries -- not with standardization in mind. As things happen, our customers liked the tools we made for our projects and the powers-that-be declared we'd be commercializing our tool set.
GeoPDF remained proprietary for pragmatic reasons -- it wasn't praticable for standardization and we didn't have the bandwidth to drive the standardization process. Moreover, it's obvious to anyone in the space -- including us! ;) -- that the days of proprietary formats have passed and at some point a well-documented standard would be promulgated. Although the PDF specification is now "owned" by ISO as ISO 32000, Adobe is still the primary shepherd of PDF, and has promulgated an open 2.0 version of our georegistration technique. Adobe is the right company to drive the standardization process -- not TerraGo -- but we're going to help in any way we can. They've done a great job with it and have done some clever things and I'll review the technique in detail when I get back from floating down the Green River in a couple of weeks. We are ecstatic that Adobe has validated our vision of ubiquitous access to geospatial information with their extensions to ISO 32000 and are working hard on having all of our products support it. Moreover, we are thrilled that ESRI has validated in the marketplace what we've been saying all along -- people other than GIS users need access to geospatial information.
Georegistration is enabling technology -- not an end in itself. Adobe is providing a platform for the development of geospatial applications on top of their technology. We've been building such "GeoApps" for almost a decade and working closely and collaboratively with Adobe [PDF] for a long time.
To get overly hung up on GeoPDF as some sort of file format is to miss what it's all about: letting professionals who don't grok GIS use geospatial information effortlessly to get their jobs done. If people don't know that they're using geospatial information on their way to making the right decision then we're doing our job.