An 8-bit unsigned integer. When sent from the client to the server, this field contains a unique 8-bit ID that can be used to identify the codec in wire traffic associated with the current connection — this ID is used in subsequent Set Surface Bits commands (section 2.2.9.2.1) and Cache Bitmap (Revision 3) orders ([MS-RDPEGDI] section 2.2.2.2.1.2.8). When sent from the server to the client, the value in this field is ignored by the client — the client determines the 8-bit ID to use for the codec.