This property specifies the offset that is in use prior to this time zone observance.
IANA and non-standard property parameters can be specified on this property.
This property MUST be specified in "STANDARD" and "DAYLIGHT" sub-components.
This property specifies the offset that is in use prior to this time observance. It is used to calculate the absolute time at which the transition to a given observance takes place. This property MUST only be specified in a "VTIMEZONE" calendar component. A "VTIMEZONE" calendar component MUST include this property. The property value is a signed numeric indicating the number of hours and possibly minutes from UTC. Positive numbers represent time zones east of the prime meridian, or ahead of UTC. Negative numbers represent time zones west of the prime meridian, or behind UTC.
This property is defined by the following notation:
tzoffsetfrom = "TZOFFSETFROM" frmparam ":" utc-offset CRLF
frmparam = *(";" other-param)
The following are examples of this property