Here is an example of a busy line:
10 A=FNX(B) . . . 50 DEF FNX(D) . . . 90 FNENDLine 10 is busy after the subprogram at line 50 is accessed and remains busy until FNEND is executed.
Here is an example of a busy program:
100 CALL X(A,B,C) . . . 140 SUB X(X,Y,Z) 150 CALL You . . . 190 SUBEXIT 200 SUB You . . . 240 SUBEXITThe subprogram X at line 140 becomes busy when it is called (line 100). The subprogram remains busy until it is exited.
Busy lines and subprograms can have an effect when editing a running program or executing LINK, DEL SUB, or DEL FN. Attempting to delete or alter a busy line causes an error message. In order to delete or alter the line, either program execution will have to be STOPped or control must be "returned" to the calling program segment (for example, RETURN, EXIT). LINK is described in page 195 .