As psusi said, the BIOS is proprietary. Vendors are free to give whatever meaning they would like to names. You should look at the context to make sense of it.
I guess you are trying to fix errors like this one:
ACPI Error: [DSSP] Namespace lookup failure, AE_NOT_FOUND (20120320/psargs-359)
ACPI Error: Method parse/execution failed [\_SB_.PCI0.SAT0.SPT1._GTF] (Node ffff8805fd4b8b90), AE_NOT_FOUND (20120320/psparse-536)
The related ACPI source is:
Name (_ADR, 0x0001FFFF) // _ADR: Address
Method (_GTF, 0, NotSerialized) // _GTF: Get Task File
Store (Zero, CMDC)
If (LOr (DSSP, FHPP))
GTFB (STFD, 0x06)
GTFB (STFE, 0x06)
GTFB (FZTF, Zero)
GTFB (DCFL, Zero)
\_SB.PCI0.SAT0.SPT1 looks like a SATA controller with its
_GTF (Get Task File) method (see ACPI spec v5, section 188.8.131.52, page 442). Therefore, the names are likely related to (S)ATA-related terminology.
CMDC is initialised to zero ands gets incremented after each
SCBF is a buffer of length 3 × 7 (=21).
GTFB sets the 7-byte field at index
CMDC to its first argument and sets byte
CMDC + 1 of
SCBF to the second argument.
SCBF is probably "SATA Command Buffer".
CMDC is probably "Command Counter".
STF enabled/disabled where
STF is an SATA feature/commands.
FHPP look like some flags that control whether
STF is enabled or disabled.
DCFL are probably some SATA features/commands.
Those features/commands can be looked up in the SATA specification I guess (exercise for the reader).
One final note, where do you usually get documentation from? From the creators, right? Perhaps source code of some BIOSes are available... ;)