ground rules

Basic guidelines or governing principles of procedural conduct in a given situation or endeavor. A reference to baseball, where the ground rules govern the rule of play specific to different ballparks. Before we begin the debate, let's establish some ground rules about what may and may not be discussed.

Basic procedures of conduct, as in The press secretary sets the ground rules for all of the President's press conferences. The term comes from baseball, where it refers to specific rules for a particular ballpark, which are based on special conditions such as a very high outfield fence or a field obstruction of some kind. It began to be transferred to more general use in the mid-1900s.