Subprogram Call: M98, M99
Function and Purpose 
          Fixed sequences or repeatedly used program can be stored in the memory as subprograms which can then be called from the main program when required.M98 serves to call sub programs and M99 serves to return from the subprogram. Furthermore, it is possible to call other subprograms from particular subprograms and the nesting depth can include as many as 8 levels.
Programming Format:-
          Subprogram call 
          M98 P__ Q__ L__ ;
          P        =        program number 
          Q       =        sequence number in subprogram to be called 
          L        =        number of sub program repetitions 
Return to Main Program from Subprogram:-
          M99 P__ L__ ;
          P        =        sequence number of return destination 
          L        =        number of times after repetition number has been changed 
Example:-
          O1234 ;
          0000000;
          ;
          ;
          M99;
          %
Notes:-
          Main programs can be used during memory and tape operation but subprograms must have been entered in the memory.
          The following commands are not the object of subprograms nesting and can be called even beyond the 8th nesting level 
Subprogram Execution 
M98 : subprogram call command 
M99 : subprogram return command 



