I was reading Wolfram's explanation at this page of what CDF is, i.e.
Today's online documents are like yesterday's paper—flat, lifeless, inactive. Instead, CDF puts easy-to-author interactivity at its core, empowering readers to drive content and generate results live.
Launched by Wolfram, the CDF standard is a computation-powered knowledge container—as everyday as a document, but as interactive as an app.
So, it seems this is a standard. But I failed to find any documentation on the format itself. Is it an open format? Can I make my own independent software which would create CDF files which CDFPlayer can play? Or am I supposed to always need Mathematica to create CDF files?