A value which indicates the set of TCP flags that this entity may potentially offers. The value is a sum. This sum initially takes the value zero, Then, for each flag, L, in the range 1 through 6, that this node performs transactions for, 2 raised to (L - 1) is added to the sum. Note that values should be calculated accordingly: Flag functionality 6 urg bit 5 ack bit 4 psh bit 3 rst bit 2 syn bit 1 fin bit For example,it you want to enable urg bit and ack bit,you should set vlaue 48(2^(5-1) + 2^(6-1)).