NASM 2.05 based x86 Instruction Reference[ch352]
A.5.326 VERR, VERW: Verify Segment Readability/Writability VERR r/m16 ; 0F 00 /4 [286,PRIV] VERW r/m16 ; 0F 00 /5 [286,PRIV] - VERR sets the zero flag if the segment specified by the selector in its operand can be read from at the current privilege level. Otherwise it is cleared. - VERW sets the zero flag if the segment can be written.