1 Pa. Code § 31.12
Except as otherwise provided by law, in computing a period of time prescribed or allowed by this part or by the regulations of the agency or another provision of law, the day of the act, event or default after which the designated period of time begins to run may not be included. The last day of the period so computed shall be included, unless it is Saturday, Sunday or a legal holiday in this Commonwealth, in which event the period shall run until the end of the next day which is neither a Saturday, Sunday nor a holiday. A part-day holiday shall be considered as other days and not as a holiday. Intermediate Saturdays, Sundays and holidays shall be included in the computation.
1 Pa. Code § 31.12
This section cited in 4 Pa. Code §607a.4 (relating to computation of time); 7 Pa. Code §179.4 (relating to computation of time); 10 Pa. Code §3.16 (relating to computation of time); 25 Pa. Code §1021.13 (relating to computation of time); 34 Pa. Code §131.15 (relating to computation of time); 37 Pa. Code §171.5 (relating to computation of time); 37 Pa. Code §197.7 (relating to computation of time); 52 Pa. Code §1.12 (relating to computation of time); 52 Pa. Code §1001.12 (relating to computation of time); 58 Pa. Code §497a.2 (relating to computation of time); 61 Pa. Code §702.12 (relating to computation of time); and 61 Pa. Code §703.2 (relating to petition content).