Format for .inf file

I am lost.
Looking for the format used in .inf file.

[Version]
signature="$Windows NT$"
ClassGUID={00000000-0000-0000-0000-000000000000}

[SourceDisksNames]
_x = %cdname%,%cdtagfile%,,""

[WinntDirectories]
1 = "\"
2 = system32
3 = system32\config
4 = system32\drivers

[SourceDisksFiles]
fasttx2k.sys = 1,,,,,,_x,4,1

[HardwareIdsDatabase]
PCI\VEN_105A&DEV_3371 = fasttx2k

[SCSI.Load]
fasttx2k = fasttx2k.sys,4



How does the line fasttx2k.sys = 1,,,,,,_x,4,1 work?

What are the fields for each section? Sorry if I am not using the right terms.