| Offset | Size (bytes) | Field | Meaning | | -----: | ------------ |
------------------- |
\--------------------------------------------------------------------------------
| | 0 | 4 | **Protocol ID** | ASCII **"TRTP"** (0x54 52 54 50). Distinguishes
Hotline from other TCP services. | | 4 | 4 | **Sub-protocol ID** |
Application-specific tag (e.g. "CHAT", "FILE"). Can be 0. | | 8 | 2 |
**Version** | Currently **0x0001**. A server should refuse versions it does not
understand. | | 10 | 2 | **Sub-version** | Application-defined; often used for
build/revision numbers. |
