string(TIMESTAMP) yields undefined %Z output on systems lacking timezone database

Goal

Determine whether CMake's string(TIMESTAMP) can reliably produce a timezone name (%Z) when the underlying system lacks timezone data, and what the expected output should be in such cases.

Constraints/Uncertainty

The command forwards the format string to the C runtime's strftime, which may return an empty string for %Z if timezone information is unavailable. Documentation notes that the behavior of %Z is platform‑dependent and undefined when the system has no timezone database, leaving an unresolved decision about whether CMake should supply its own timezone data or define a fallback.

Questions

• Should string(TIMESTAMP) return an empty string, a fixed value like “UTC”, or signal an error when %Z is used without available timezone data?
• Is there a planned mechanism to let users specify an explicit timezone identifier for portable offset or name generation?
• Can developers safely rely on %Z for programmatic parsing given its variability across platforms and environments?