Each activation of a procedure has its own distinct values for automatic (or local) data, and each activation may have different actual parameters or arguments. An activation number can be used to specify the environment for evaluating or displaying variables and procedure arguments. An activation number can also be used when setting a breakpoint in a particular activation of a procedure.
If the activation number is omitted from the name, the debugger uses a default of 0, the most recent activation. The only exception to this is Breakpoint, where omitting the activation number means that a breakpoint is to be taken on every activation of the procedure.