Manual should explain what is meant by "rotation".

[grahamgower]

Curiously, I couldn't find a description of precisely what is meant by log rotation. Does the current log get moved? Copied? Truncated? If a process has an open file handle, what behaviour can I expect from the program when that file is logrotated? What about races with other cron jobs that append to a logrotated file?

[kdudka]

Curiously, I couldn't find a description of precisely what is meant by log rotation.

Sounds like we should add one.

Does the current log get moved? Copied? Truncated?

This actually depends on the (no)copy, (no)copytruncate, and (no)renamecopy configuration directives.