Kind of related question: why are no whitespaces allowed in many passwords while special characters are? I'm a huge fan of elaborate nonsense sentence passphrases but get shot down.
(I ask cause that regex has that requirement it seems)
I have no idea if this is true or not but I was told it harkens back to very early multi-user operating systems where user credentials were stored unencrypted in plaintext files that used white space as delimiters.
I tend to believe this might be accurate because I learned programming back in the 1980’s on an Onyx Systems microcomputer. There was a bug that some of us learned about in its rudimentary email program that would dump you into its otherwise-protected system directory. In that directory was a file containing both usernames & passwords in clear text. I don’t recall if it used white space as a delimiter, but given everything was in clear text and not encrypted I think that might have been the case.
Oh boy, having done data science work with government files, you remind me that they still use terrible delimiters. A white space delimiter sounds significantly worse than a tab delimited file, though!
I learned COBOL programming on that system. COBOL’s sequential file data type was all about space-delimited text files. Part of a program would define the various input & output files. For example a numerical userid might take up columns 1-8 then the first initial would be in column 10 then the last name in columns 12-20 and so on…
Tabs are considered white space. A white space is technically any character that is not visible. That covers things like spaces, vertical/horizontal tabs, non-breaking spaces, zero-length spaces, etc.