Any time for different 
GameSpyFilterQueryStr gslist generates special magic byte
"gslist.exe  -o 4 -n battlefield2 -f  
GameSpyFilterQueryStr  -X \hostname"
Send data (Second byte $78)
Code:
00000000  00 78 00 01 03 00 00 00  00 62 61 74 74 6C 65 66   .x...... .battlef 
00000010  69 65 6C 64 32 00 67 73  6C 69 76 65 00 3A 37 69   ield2.gs live.:7i 
00000020  2B 42 7D 4C 5F 6E 75 6D  70 6C 61 79 65 72 73 20   +B}L_num players  
00000030  3E 20 30 20 61 6E 64 20  67 61 6D 65 76 65 72 20   > 0 and  gamever  
00000040  3D 20 27 31 2E 35 2E 33  31 35 33 2D 38 30 32 2E   = '1.5.3 153-802. 
00000050  30 27 20 61 6E 64 20 67  61 6D 65 76 61 72 69 61   0' and g amevaria 
00000060  6E 74 20 3D 20 27 70 72  27 00 5C 68 6F 73 74 6E   nt = 'pr '.\hostn 
00000070  61 6D 65 00 00 00 00 01                            ame..... 
Can you point me to that function that are responsible for generation of this byte ?