Period.pm is a Perl module that contains code to deal with time periods. Currently, there is only a function in this module. That function is called inPeriod(). inPeriod() determines if a given time is within a given time period. It will return 1 if it is, 0 if not, and -1 if either the time or the period passed to it were malformed. The time is specified in non-leap year seconds past January 1, 1970, as per the time() function. The period is a string which is of the form described in Period's man page.