In this Chapter, the word "day" means a calendar day. In computing any period of time prescribed or allowed by the rules in this Chapter, the day of the act, or event, from which the period of time begins to run will not be included. The last day of the period will be included, unless it is a Saturday, Sunday, legal holiday, or other day when the Office of Personnel Management does not remain open for public business until 4:30 p.m. In such case, the period will run through the end of the next day the Office of Personnel Management is open until at least 4:30 p.m.
Okla. Admin. Code § 695:10-1-12