Like a label value, an entry value is a descriptor containing two parts. The first part designates an entry point of a procedure, and the second part designates a stack frame of the block in which the procedure is declared. The second part of an ENTRY value that designates an external procedure is null.

The second part of the entry value is relevant only when there is more than one activation of a given procedure, as is the case with recursive procedures; otherwise, an entry value can be considered simply as a designator of an entry point.

Entry values can be assigned, compared for equality or inequality, passed as arguments, and returned from functions, but no calculations or conversions can be performed on them, and they cannot be transmitted in stream I/O.

The following discussion explains the second part of the entry value, called the stack frame designator.