Texas Instruments TI-83 PLUS - Manual (Page 539)

TI-83 Plus Programming 536
Program Output
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Subroutine ( '
Notes about Calling Programs
Variables are global.
label used with Goto and Lbl is local to the program where it is located.
label in one program is not recognized by another program. You cannot
use Goto to branch to a label in another program.
Return exits a subroutine and returns to the calling program, even if it is
encountered within nested loops.