joeu2004 presented the following explanation :

[...]
"Bruno Campanini" wrote:
Then, why not to take into account number in I39 and text in I40?

Perhaps the author of the code knows that if I39 meets the condition(s)
tested, I40 is never text. There is nothing wrong with that, IMHO; but I
know that some purists insist on making every bit of code bulletproof. It's
a judgment call.

Well, when I missed to consider I39 can contain a text, that's my
fault.
When you did the very same thing with I40 "Perhaps the author ..., I40
in never text".

Poor man!

I switch off the thread, save your ink! I will not read you any longer.

Bruno