What is subprogram?

Some articles on subprogram, subprograms:

IBM 1130 - Programming - Subprograms
... Most subprograms were called with the instruction BSI (Branch and Store IAR) ... Subprograms returned to wherever they were called on that occasion using an indirect branch through that first word of the subprogram ... So a subprogram named SIMPL might be organized as follows SIMPL DC *-* This is the entry point, filled with a zero initially ...
G-code - Specific Codes - List of M-codes Commonly Found On Fanuc and Similarly Designed Controls
... (APC) M For machining centers with pallet changers M98 Subprogram call M T Takes an address P to specify which subprogram to call, for example, "M98 P8979" calls subprogram O8979 ... M99 Subprogram end M T Usually placed at end of subprogram, where it returns execution control to the main program ...
SPARK (programming Language) - Verification Conditions
... certain properties hold for a given subprogram ... attempting to establish that the following run-time errors cannot occur within a subprogram array index out of range type range violation division by zero ... will hold for all possible paths through the subprogram ...
Subroutine - Local Variables, Recursion and Reentrancy
... A subprogram may find it useful to make use of a certain amount of scratch space that is, memory used during the execution of that subprogram to hold intermediate results ... has a return address that tells it where to pass control back to when the subprogram finishes ... A subprogram may have any number and nature of call sites ...