This seems like a regular expression. There * is not a wildcard but a quantifier. It means that the preceding character or group can occur zero or more times. . is a wildcard. It means any character except newline. [...] is a character set. It means any character from the set.
. is a wildcard for one character.
.* is a wildcard for any number of characters.
[.] means exactly one dot.
.{4} means four wildcards.
You can use sandboxes and cheatsheets like https://regexr.com/ to test your regular expressions.
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solved Input mask wildcards in a PLC language, i need to represent 4 characters [closed]