I was using a method suggested to compare each character against a list of alphanumeric characters, for my purpose to exclude punctuation. However, I found that:-
a) the combination of using 'list from CSV row' and 'join' to make make a list of acceptable characters, if you include a space (eg, comma-space-comma), this gets compressed to a double quote in the eventual list used for the comparison. So it doesn't recognise spaces...
b) ...but even worse, it also accepts punctuation as valid. The double quote in the list of characters to compare to the test character seems to make every character acceptable, that I've tested.
I've found a way round it: Create your list first, and use 'add items to list' with a space in quotes. This makes into the list as a separate character then and correctly allows spaces when they are in the list, and doesn't allow punctuation when they are excluded from the list. eg.
