subtracting header_length from TAG_MAX_CARGO_PLUS_HEADER_WRITE ?

[bradcar]

It looks like in shtp.c it gets the advertisement value of TAG_MAX_CARGO_PLUS_HEADER_WRITE, but then it subtracts the SHTP_HDR_LEN (=4) from value return. But the tag names implies it should have the header length in it? Why is this?

In Line 460:

            case TAG_MAX_CARGO_PLUS_HEADER_WRITE:
                x = readu16(val) - SHTP_HDR_LEN;
            
                if (x < SH2_HAL_MAX_PAYLOAD_OUT) {
                    pShtp->outMaxPayload = x;
                }
                break;