I was able to find the full range of functions defined in the OS/2 4.5 toolkit's .h files, and will use my CAlive source code parser to read the source files, load them into Wiki pages for full parameter-based documentation, creating a fully documented developer help system (to be added to the EDM/2?).
Maybe after it's completed, someone can read the Presentation Manager documentation, and add in the missing verbal descriptions over time, or at least cite the pages the functions fall in/on.