USERCAPSIN Field - ulFunction

 ulFunction (ULONG) 
    Specifies the QUERYCAPS, QUERYCAPSLIST, or SETCAPS subfunctions. 

    The subfunctions, specified by the ulFunction field of the USERCAPSIN 
    structure, may be defined as follows: 

    QUERYCAPS            

                         #define  QUERYCAPS     1L
                         

                         QUERYCAPS returns the number of capabilities and 
                         capability descriptions in the buffer area 
                         pointed to by pOut. 

                         Because the values for each capability are not 
                         yet allocated, the pValueList, pCurrentValue, and 
                         pDefaultValue fields in the DRIVERCAPS structures 
                         must not be filled in for this call. 

                         The driver must ensure that the buffer area size, 
                         specified by ulSize, is sufficient for the 
                         supported number of capabilities. If not, the 
                         driver should return the number of capabilities 
                         supported in the first word of the buffer area 
                         and a return code of RC_ERROR. The driver will be 
                         reinvoked with a larger buffer area for 
                         QUERYCAPS. This allows a driver to export 
                         multiple capabilities (each, in turn, gets its 
                         own page in the System Object notebook). 

    QUERYCAPSLIST        

                         #define  QUERYCAPSLIST   2L
                         

                         QUERYCAPSLIST fills the pValueList, 
                         pCurrentValue, and pDefaultValue fields in the 
                         DRIVERCAPS structure pointed to by pOut. The 
                         members must be 0 padded up to the length 
                         specified by ulValueMemberSize. 

    SETCAP               

                         #define  SETCAP    3L
                         

                         SETCAP sets a value that the user has selected. 
                         The value is specified in the pCurrentValue field 
                         of the DRIVERCAPS structure pointed to by pOut.