Bit Field Guide

Data Offset

Transport 4 bits TCP segment unverified

Header length in 32-bit words. Five means no options.

Where it sits

TCP Segment > Data Offset

Open in the explorer — TCP over IPv4, in a protected QoS Data frame, aggregated
Open in the explorer — TCP over IPv4, in a protected QoS Data frame
Open in the explorer — TCP over IPv4, in an open QoS Data frame

Accuracy

Clause: RFC 9293 §3.1
Verified: Not verified against the standard. Treat this as a claim, not a fact.