Q: How is the dlsDelta field in PRAM's time zone
MachineLocation record used and set?
A: The high bit (bit 7) of the dlsDelta field represents
the current state of daylight savings time. If daylight savings time
is in effect, then bit 7 of dlsDelta is set; if daylight savings time
is not in effect, then bit 7 is clear. The other 7 bits (bits 0 through 6)
of dlsDelta are reserved for future use by Apple. Thus, it's important that
you preserve its current value if you ever use
WriteLocation to set the value of
gmtDelta. See the description of the
WriteLocation routine in "WorldWide Development:
Guide to System Software," available on the latest Developer CD
for details on getting and setting
gmtDelta while leaving dlsDelta
intact. In short, the code looks like this:
VAR
myLocation: Location;
myGMTDelta: LongInt;
tempSignedByte: SignedByte;
:
tempSignedByte := myLocation.dlsDelta;
myLocation.gmtDelta := myGMTDelta;
myLocation.dlsDelta := tempSignedByte;
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[Mar 26 2001]
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