Whenever periods of time are specified in this part in days, calendar days are intended. When the day, or the last day fixed by statute or by regulation under this part for taking any action or paying any fee in the Office falls on a Saturday, Sunday, or Federal holiday within the District of Columbia, the action may be taken, or the fee paid, on the next succeeding day that is not a Saturday, Sunday, or a Federal holiday.
37 C.F.R. §2.196
Part 3 pertaining to both patents and trademarks is placed in the grouping pertaining to patents regulations.
Part 4 is placed in the separate grouping of parts pertaining to patents regulations.
Part 5 is placed in the separate grouping of parts pertaining to patents regulations.