NFRs and QA (or QC) --- A way of measuring the maintainability of the software, part 1 --- Halstead Complexity, 1977 en.m.wikipedia.org/wiki/Ha…measures www.win.tue.nl/~asereb…1/10.pdf --- It also allows to predict the number of bugs in the software, and the accepted error ratio, which might be very useful for QA / QC activities and quality goals