CHECK(OPCS)             Optical Printer Control System          CHECK(OPCS)

    NAME
        check  - check counter values for specific channels

    USAGE
        check <chans> <val[,val..]>

        Where:
            <chans> is a list of channel letters (abc..)
            <val[,val..]> is a comma separated list of counter values,
                          one for every channel in <chans>

    EXAMPLES
        check f 1000        -- check f channel's counter is 1000
        check fg 1000,2000  -- check f counter is 1000 and g is 2000

    DESCRIPTION
        This command helps verify counter values are where they should be
        in RUN(OPCS) scripts.

        It lets the author check to see if the specified channels' counters
        are what the author expected them to be.  This helps catch errors
        during script programming + shooting.
        
        If a comparison fails, an appropriate error warns of the discrepancy,
        and prompts the operator with an ABORT/CONTINUE option.

        It's expected that for the channels specified, the exact same number
        of counter values are specified for each channel.

        Counter values must be comma delimited, and can either be numeric,
        math expressions, or feet/frame format. Example:

            check ab (150-10),13'4   -- check if a's counter is 140
                                        and   if b's counter is 13'4

            check a (pro)            -- check if aerial projector (a)
                                        counter same as main projector (pro)

            check ab (cam+5),(cam+5) -- check if pro2 and pro2's counters
                                        are same as camera's counter +5.

        Note in OPCS the 'a' channel is the aerial projector, 'b' is the
        main projector, 'c' is camera, and 'd' is the fader shutter.

    HISTORY
        Early OPCS versions only managed cam/pro/shu, so CHK(OPCS) was designed
        for that. Motion control channels were later added, the newer CHECK(OPCS)
        was added, allowing *any* motor channel to be checked. CHK(OPCS) is kept
        for backwards compatibility, and syntactically simpler to use.

    SEE ALSO
        CHK(OPCS)    - older command that only checks frame counters and fader
        RUN(OPCS)    - run an OPCS script file
        MOTORS(OPCS) - enable/disable motors for debugging scripts

    ORIGIN
        Gregory Ercolano, Altadena California 05/28/20