BNETDocs
S>C 0x1C SID_STARTADVEX3
Message Id:0x1C
Message Name:SID_STARTADVEX3
Direction:Server to Client
Used By:Diablo II, Diablo II Lord of Destruction
Diablo Retail, Diablo Shareware
Starcraft Japanese, Starcraft Broodwar
Starcraft Shareware, Starcraft Original
Warcraft II BNE
Format:

(UINT32) Status 

Remarks
Possible values for Status:
0x00: Ok
0x01: Failed
Leaky
Comments
jtrumbull

The server doesn't appear to respond with this packet when using the D2XP client.