get "0" to work in classifications

[#1]

Please get "0" to work in classifications.

Current behavior: 0 is ignored in any classification column

Exprected behavior: 0 is treated as any other character while importing

[#2]

I second that one.

A few month ago I did some tests. A blank is also not allowed as first character. I'd recommend to allow classification of i.e. " hello", too.

Other restrictions (probably ok to let them "forbidden"):

";" is not allowed at all. Neither is "crlf" (don't ask). And of course "#".

[#3]

I just came across this idea that dates from 7 years ago ... and nothing has changed!