FILE_USE_FILE_POINTER_POSITION in FastIo?

NTFSD
1

In IRP_MJ_READ,there is the rule:
(IrpSp->Parameters.Read.ByteOffset == NULL) ||
(IrpSp->Parameters.Read.ByteOffset.LowPart == FILE_USE_FILE_POINTER_POSITION
&& IrpSp->Parameters.Read.ByteOffset.HighPart == -1)

In IRP_MJ_WRITE,there is the rule:
( IrpSp->Parameters.Write.ByteOffset.LowPart == FILE_WRITE_TO_END_OF_FILE
&& IrpSp->Parameters.Write.ByteOffset.HighPart == -1 )
(IrpSp->Parameters.Write.ByteOffset == NULL) ||
(IrpSp->Parameters.Write.ByteOffset.LowPart == FILE_USE_FILE_POINTER_POSITION
&& IrpSp->Parameters.Write.ByteOffset.HighPart == -1)

my question is:
are the rules still in fastio?
In the docs about fastio,I can’t find the description about the rules.

2

I think,these magic numbers don’t occurs in fastread and fastwrite.
Anybody can give me a answer?thanks~~~