Marks the beginning of a multi-line block of code to be executed as a thread.
threadBegin; m = n*p; n = calcA(m); threadEnd;
Notice that the writer-must-isolate rule (see Multi-Threaded Programming in GAUSS)
does not apply within the bounds of the
threadEnd pair, as there is no risk of
simultaneous access to a symbol. The rule only applies between the threads in a given set (and their children).
threadJoin for an example of a fully-defined thread set.