The value is to remark When yellow action is remarking.
For remark-dscp-pass, the range is 0~63;
For remark-ip-pass and remark-mplsexp-pass, the range is 0~7;
Only software QoS support this node.
255 is returned only when getting value from hardware QoS or
when action being pass, discard of software QoS.
255 can't be set.