My thanks to both
ChocolateFactory and
Zorak for their help. Both their answers worked.
After playing with it for a while and coming back to this thread, I found what I should have done all along:
Look at the thread's WIKI. There is a
link to a wonderful thread completely dedicated to ITA/Matrix faring specifications and issues. I am sure I had found it several years ago and had completely forgot about it.
It is dated from 2004 and is for a version of the software but I have found that the faring specs shown there all seem to be completely relevant to the current version.