The Scotland Act 1998 (Transitory and Transitional Provisions)(Standing Orders and Parliamentary Publications) Order 1999

Rule 2.1 Session of the Parliament

3.  A sitting day is any day when the office of the Clerk is open but not when the Parliament is in recess or dissolved. The Parliament shall decide, on a motion of the Parliamentary Bureau, the days on which the office of the Clerk is to be open. Until the Parliament has so decided, the Presiding Officer shall appoint those days. The days on which the office of the Clerk is to be open shall be notified to members by the Presiding Officer.