LAS\GET [N]
GET copies R into T, and loads the Observation number N in R. The
current index initialized by FIND is first explored, then, if needed,
the whole input file. If N is absent, the previous (last read)
Observation is recovered. If N is FIRST, the first Observation of the
current index is loaded. If N is NEXT, the next Observation in the
current index is loaded.