From Xojo Documentation

Read-Only Property (As Double )
DoubleValue = aDate.GMTOffset

Supported for all project types and targets.

The difference between local time and Greenwich Mean Time (aka UTC) in hours. Changing the GMTOffset changes the time stored by the Date object.

Sample Code

The following code changes the GMT offset.

Dim d As New Date
d.Day = 13
d.Month = 8
d.Year = 1956
d.GMTOffset = -7