The field is a fixed length, gated by the constant &cw(RMR_MAX_XID) and if len is larger
than this value, only RMR_MAX_XID bytes will actually be copied.
The field is a fixed length, gated by the constant &cw(RMR_MAX_XID) and if len is larger
than this value, only RMR_MAX_XID bytes will actually be copied.