NAME
        CxObjError -- obtain a commodity object's accumulated error. (V36)

   SYNOPSIS
        error = CxObjError(co);
        D0                 A0

        long cxobjerror(cxobj *);

   FUNCTION
        When a function acting on an object fails, it records the failure
        in the object. This function returns the accumulated error value.
        The values are represented by flag bits defined in
        <libraries/commodities.h>. several errors may be recorded by multiple
        bits in 'error'.

        The currently defined errors are:

        COERR_ISNULL
          The value of parameter 'co' was in fact NULL. This error
          means "the problem with the object you inquire about is
          that it failed to be created."

        COERR_NULLATTACH
          Using the commodities' list manipulation functions, an attempt was
          made to add a NULL object to the list belonging to 'co'. This allows
          a line of code as follows to exist in an error-tolerant program:

            AttachCxObj(filter,CxSender(myport,MY_ID));

        COERR_BADFILTER
          The most recent filter specification for a filter object
          was faulty. This happens if no sense can be made out of a
          description string, or if an input expression (IX) has an
          invalid format or version byte. When this bit is set in a
          filter's error field, the filter will match nothing, but this
          is not the proper way to "turn off" a filter, use activatecxobj().

        COERR_BADTYPE
          A type specific operation, such as setfilterix(), was called
          for object 'co', but 'co' isn't of the proper type.

   INPUTS
        co - the commodity object to get the accumulated error from (may be
             NULL)

   RESULTS
        error - the accumulated error, or 0 if 'co' is NULL

   SEE ALSO
        setfilter(), setfilterix(), attachcxobj(), activatecxobj(),
        clearcxobjerror()