Use Dropbox file revision for change-detection / core api

Hello,
i would like to use the revision of a file to detect for change. Normally i would use its timestamp and or file-size on my local file system.
But the dropbox-revision seems to be a good alternative.

Now my question is, if the revision is dropped after 30 days (no pro or business account),
how is the revision number changed,
is it set to zero?

so i could detect this change as a reset.

i am not using dropbox since 30 days so your info would be helpful..

Best regards,

Martin