What does this version number mean?

Sometimes I joke that it reflects the degree of proximity of the text to the Absolute Truth.

In reality, though, I start numbering the versions from something like 0.1 or 0.3, depending on how much of it I write down; then I start running them through widening circles of people who are likely to give me intelligent feedback. This is my favorite stage. Then I listen to criticism and modify the text, adding 0.01 each time. Versions 0.65 to 0.75 are already decent and finalized enough to run through one or two professional editors. Versions 0.80+ have been read by at least several hundred people, and go to some off-line publisher. After that, I may still put more changes in - but usually by this time I am too busy playing with some other ideas.
A version number like 0.84-3 means that it's the third HTML edit on the same text.