The PLOptionTable structure is used by
      plMergeOpts to pass information on user-defined command line
      options to PLplot. The structure contains the following fields:
    
opt
	  (PLCHAR_VECTOR)
	Name of option.
handler
	  (int (*func) (PLCHAR_VECTOR, PLCHAR_VECTOR, PLPointer))
	User-defined handler function to be called when option is set. A NULL value indicates that no user-defined handler is required.
client_data
	  (PLPointer)
	A pointer to client data. A NULL value indicates that no client data is required.
var
	  (PLPointer)
	A pointer to a variable to be set to the value specified on the command-line option.
mode
	  (long)
	
	    Type of variable var. Allowed values
	    are PL_OPT_FUNC, PL_OPT_BOOL, PL_OPT_INT, PL_OPT_FLOAT,
	    PL_OPT_STRING.
	  
syntax
	  (PLCHAR_VECTOR)
	Syntax for option (used in the usage message).
desc
	  (PLCHAR_VECTOR)
	Description of the option (used in the usage message).