In the UK Minimum wage regulation this is the term used (presume you're asking for British terms !? See below how It's used:
"Regulation 22: sets out how to calculate the hours of salaried hours work where the worker has worked for
longer than the basic hours under the contract. This maintains the principle that the worker should be paid the
national minimum wage on average for every hour worked. When excess hours are worked, Regulation 22
applies instead of Regulation 21. Regulation 22 accordingly contains a different definition of "basic hours",
based on whether the hours in the worker’s contract are varied upwards or downwards during the year; and on
how many variations have been made. The purpose of this calculation is to establish the correct start-point in
each case from which the excess hours must be counted.
Regulation 22: also defines what is meant by the "calculation year" for the contract, which will run differently
for workers already employed on 1 April 1999 (when the Regulations are due to come into force) and workers
who start with a new employer after that time."

My second reference is Norwegian document which demonstrates how the term is used in contracts with a University, from which you can deduct that "grunntid" is basically equivalent to "basic hours"



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Note added at 2002-03-22 10:07:09 (GMT)
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oops! My a\'s seem to be falling out of the text. Sorry!