['i' <set1> <set2>]
A boolean opperation. Usually tests the existence of a given entity (watch the '
\' which prevents the value beeing replaced by its content!):
And it checks if at least one node included in set1 is inside the elements included in set2:
test i nodeset elemset
Or it tests the observability 'o' of a certain node under the given orientation of the model. The node can be given as a member of a set or directly by its node-nr. The command returns TRUE or FALSE and writes it to the ”stack”.