28 struct vop			/* vax instruction operand                 */  struct
30   short int vop_ndx;		/* -1, or index register. eg 7=[R7]	   */  argument
31   short int vop_reg;		/* -1, or register number. eg @I^#=0xF     */  argument
33   short int vop_mode;		/* addressing mode 4 bits. eg I^#=0x9	   */  argument
34   char vop_short;		/* operand displacement length as written  */  argument
36   char vop_access;		/* 'b'branch ' 'no-instruction 'amrvw'norm */  argument
37   char vop_width;		/* Operand width, one of "bdfghloqw"	   */  argument
38   const char *vop_warn;		/* warning message of this operand, if any */  argument
39   const char *vop_error;	/* say if operand is inappropriate         */  argument
40   char *vop_expr_begin;		/* Unparsed expression, 1st char ...	   */  argument
41   char *vop_expr_end;		/* ... last char.			   */  argument
42   unsigned char vop_nbytes;	/* number of bytes in datum		   */  argument