TNS Data Packet Structure

Byte 0-7 is the header

Byte 8-9 is the data flag.  0x0040 indicates a disconnect packet.  0x0000 indicates normal data.

Byte 10 determines what is in the data packet

Type	Description
0x01	Protocol negotiation.  The client sent to the server the protocol versions acceptable (e.g. 6, 5, 4, 3, 2, 1, 0).  The server will response with the common version and other information such as character set, version string and server flags
0x02	Data type representation exchange
0x03	Two-Task Interface (TTI) function call 0x02 Open 0x03 Query 0x04 Execute 0x05 Fetch 0x08 Close 0x09 Disconnect/logoff 0x0C Autocommit ON 0x0D Autocommit OFF 0x0E Commit 0x0F Rollback 0x14 Cancel 0x2B Describe 0x30 Start up 0x31 Shutdown 0x3B Version (will be called before authentication) 0x43 K2 Transactions 0x47 Query 0x4A OSQL7 0x51 Logon (present password) 0x52 Logon (present userid) 0x5C OKOD 0x5E Query 0x60 LOB Operations 0x62 ODNY 0x67 Transaction end 0x68 Transaction begin 0x69 OCCA 0x6D Start up 0x73 Logon (present password – send AUTH_PASSWORD) 0x76 Logon (present username – request AUTH_SESSKEY) 0x77 Describe 0x7F OOTCM 0x8B OKPPC
0x08	Indicate OK – send from server
0x11	Extended TTI functions 0x6B Switch or detach session 0x78 Close 0x87 OSCID 0x9A OKEYVAL
0x20	Used when calling external procedures with service registration
0x44	ditto