awk bug (or is it a feature)

[pjbk at hwcs.UUCP]

Our version of awk does not allow one to use a field specified
by a numerical expression as the left hand side of an expression.

The file below will pass the standard input through unmodified,
although it is designed to replace the last field in each record
with "LAST FIELD".  Is this a bug or a feature?
 -----------------------
 { $NF = "LAST FIELD"
 print}
 -----------------------
-- 
	Peter King, Heriot-Watt University
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