IndexedDB versioning question

I’ve been playing with IndexedDB a bit and have noticed under “onupgradeneeded” (W3C draft) that the version datatype is an unsigned long.

Maybe I have blinders on, but I’m used to versioning like

[major revision] dot [minor revision] dot [tweak revision]

So I’m wondering why an unsigned long? Is this needed for a versioning convention I’m unaware of? Negative versions?

I’m also wondering how the API deals with 2 decimals, doesn’t seem like a long would do it.

I guess I’d better leave off the “tweak” revisions until I know better.