As their name implies, elapsed timers count up. There are two types of elapsed timers in SPLat:
SPLat 8 bit controllers (green boards) do not support the use of task timers if Multitrack multi-tasking is not running. In addition, on these controllers you cannot use Pause, WaitOnT, WaitOffT or WaitOnKT between a MarkTime and its corresponding fSTSinceMark or LoopIfTiming.
SPLat 32 bit controllers (black boards) have none of these restrictions. So you can use task timers on a SPLat 32 bit controller even if you are single tasking and can use any of the Pause or Wait instructions together with MarkTime and its siblings.
See MultiTrack tutorial.