alt-255 isn't a nul (binary zero)
Hey G. I'm sure there are other definitions but mathematically, null is not zero.
Null is a non value or a set containing nothing. If you put zero in that set, it's no longer null, it's zero.
We're not talking about set theory but about character codes.
https://www.w3schools.com/charsets/ref_html_ascii.asp
Char Number Description
NUL 00 null characterIf you type ALT-255 into a Windows program (because this is a Windows trick) the cursor advances one character. If you can switch to binary and look at the hex code, it's A0 = 160 decimal, and in HTML, that is a no-break space.
https://www.w3schools.com/charsets/ref_html_8859.asp
Character Entity Number Entity Name Description
  non-breaking spaceAlt +3 digits in Windows gives you the character from the original IBM PC DOS character set: CP437.
https://en.wikipedia.org/wiki/Code_page_437The table has 0 as "NUL" and 255 as "NBSP", with the note:
"0, 32 (20hex) and 255 (FFhex) all draw a blank space. The use of 255 for U+00A0 Non-breaking space (NBSP) has precedent in word processors designed for the IBM PC."
Anyway, I know what alt255 is but it's also null because it has no value. A computer treats it as an actual character. If you name a folder alt+255 the folder appears to have no name (because alt255 is invisible)
Computers treat it however the programmer determined.
I guess what was happening is that the search term input was set to reject an empty or normal space input. But let the nbsp through. How it was treated then, as a normal space or nbsp or empty who knows.
So this was a trick that got you past the "blank" filter.
Anyway, we don't need it now as you can just leave the search term empty and it will work.
There are lots of invisible characters.
There are a few dozen listed on this page:
https://www.w3schools.com/charsets/ref_utf_punctuation.asp