Time counting is vague in documentation of set_time_limit

This part of documentation

The set_time_limit() function and the configuration directive max_execution_time only affect the execution time of the script itself. Any time spent on activity that happens outside the execution of the script such as system calls using system(), stream operations, database queries, etc. is not included when determining the maximum time that the script has been running. This is not true on Windows where the measured time is real.

is vague. For example, waiting for a flock() call to return does count or not in time spent?

Start with the set_time_limit() documentation and the quoted explanation of max_execution_time. Verify whether time spent waiting for flock() is counted, including the Windows distinction, then revise the wording to state the behavior clearly and add an example if needed. Done means the documentation unambiguously explains which waiting operations contribute to the limit.