It depends on the batch parser.
;,=
are general batch delimiters, so you can append/prepend them to the most commands without effect.
;,,= ,=; echo hello
;,cls,;,,
The .
dot can be appended to the most commands, as the parser will try to find a file named cls
(without extension) cls.exe
cls.bat
, and when nothing is found then it takes the internal command.
The opening bracket is also a special charcter that the parser removes without error.
The \
backslash is used as path delimiter, so sometimes it works but sometimes you could change even the command.
cls\..\..\..\windows\system32\calc.exe