[JoeKustra]

Does 'RC6...' refer to a 'Release Candidate' version?

Yes. However, it's been standard with software releases for the last few years. It saves typing too, since it's easier to enter RC6 rather than the whole number.

 

[JoeKustra]

Does TiVo usually send release candidates to all its customers?

It would be unusual to receive a software release without an RC number.