The characters * and # are line comment characters; each start a comment at the beginning of a line, but only at the beginning of a line. A # prefixes a hexadecimal number if found elsewhere on a line.
Two other characters, % and !, each start a comment anywhere on the line. Thus you can't use the modulus and not operators in expressions normally associated with these two characters.
A ; is a line separator, treated as a new-line, so separate instructions can be specified on a single line.