On a recent question I asked about a scripture in Acts I had trouble coming up with appropriate tags. Another user edited the question and added tags, including acts (lowercase first letter). Does the tag refer to deeds or to the book of Acts? If the latter, shouldn't it be capitalized?
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None of the tags are capitalized. It's a StackExchange convention.
In this case, the Acts tag refers to:
The fifth book of the New Testament, giving an account of the lives of the apostles after Jesus' death and resurrection, and the development of the early church.