Clipboard Status Codes

Possible clipboard status codes are listed below. Negative values are used because m_cb_read uses positive values for partial completion status.

CB_OK        0        Success.  
CB_LOCKED   -1        Clipboard access denied.  
CB_NOT_OPEN -2        Clipboard not formally open.  
CB_ALLOC    -3        Heap allocation failure.  
CB_EXISTS   -4        Representation already exists.  
CB_REP_OPEN -5        A representation is open.  
CB_NO_REP   -6        No representation open.  
CB_NO_SUCH  -7        No such representation.  
CB_BOUNDS   -8        Transfer request out of bounds.