A check box is a choice with associated text that requires a true/false, yes/no, on/off answer.

• It must be an alphanumeric field of length 1.
• Check boxes are defined through the CBOX input/output attribute. The maximum number of check boxes that may be defined for a function is 999.
• Identification must be either label (*LABEL) or no identification (*NOID). Label is the default.
• Within RDML the valid values for a check box field are "1" for selected and " " for unselected. Use of other values may produce unpredictable results.
• When on a NPT screen a check box is selected with a "/" or country-designated character (defined in the DC@OSVEROP *SELECTCHAR=x option) and unselected with a " ". This character is locked in at compile time for the best performance when executing.
• LANSA generated code handles the conversion between screen and RDML values for check boxes (i.e. from "/" to "1" when selected).
• A new system value named *CHECKBOXSELECTED has been created to be used when testing the return value of a check box field. Use of this system variable makes your RDML code "self-documenting".
• A check box may only contain one of two values. Therefore the best way to test its value is to check if it is *EQ (equal) or *NE (not equal) to the selected value (*CHECKBOXSELECTED).
• To test if a check box has been selected:

        BEGIN_LOOP
          REQUEST    FIELDS(#SCREEN)
          IF         COND('#CBOX01 *EQ *CHECKBOXSELECTED')
            MESSAGE  MSGTXT('Check box 1 is selected')
          ENDIF
          IF         COND('#CBOX02 *NE *CHECKBOXSELECTED')
            MESSAGE  MSGTXT('Check box 2 is not selected')
          ENDIF
        END_LOOP

the correct way to initialize check boxes:

     CHANGE     FIELD(#CHECKBOX1 #CHECKBOX2 #CHECKBOX3 
                      #CHECKBOX4) TO(*NULL)
 
     IF        COND('#ACTIVE *EQ ''Y''')
       CHANGE  FIELD(#CHECKBOX2) TO(*CHECKBOXSELECTED)
     ENDIF
 
    CHANGE     FIELD(#CHECKBOX4) TO(*CHECKBOXSELECTED)