pspdfppd,
I guess it was put there in case there would be spaces. Because this formula is put on a public newsgroup and anyone can use it, it may have been put there to ensure that anyone who copies the data would be able to use the formula without errors, even if their data have spaces. Also, since we don't have your data in hand, he might have wanted to write something that would be certain to work in all cases, spaces or not.
In other words, it's just extra safety to make sure that the expression worked when you copy it. If you don't need the trims, feel free to remove them.
Regards,
Rapha