Many governmental jurisdictions have promulgated regulations dictating that local clocks be adjusted at certain times of the year –e.g. during summertime or certain religious events. Commonly known as "Daylight Saving Time", "Summer Time" or "Ramadan Time", special care must be taken when configuring events that occur near or during a transition from "standard" time to "daylight saving time" and vice-versa. There are two basic types of such transitions; a "spring forward" transition, during which the local clock is advanced some period of time (typically an hour) and a "fall back" transition, during which the local clock is set back some period of time (again, typically an hour).
When "springing forward", the local clock will simply skip past certain time values. For example, imagine that we have a transition where, at 02:00:00 exactly (2:00:00 AM), the clock will be advanced 1 hour. A digital clock counting through this transition would show values like:
[...]
01:59:57
01:59:58
01:59:59
03:00:00
03:00:01
03:00:02
[...]
In this example, the entire 2 AM hour simply doesn't exist. Hence, any RDCatch events that reference such events will not be executed.
"Fall-back" transitions have the exact opposite behavior. Specifically, the time period over which the transition occurs is duplicated. For example, imagine that we have a transition where, at 02:00:00 exactly (2:00:00 AM), the clock will be set back 1 hour. A digital clock counting through this transition would show values like:
[...]
01:59:57
01:59:58
01:59:59
01:00:00
01:00:01
01:00:02
[...]
The end of the second 1 AM hour then proceeds normally:
[...]
01:59:57
01:59:58
01:59:59
02:00:00
02:00:01
02:00:02
[...]
When dealing with a transition of this sort, RDCatch will treat times that occur within the transition as belonging to the first pass; with the all times in the second pass being ignored.