There are a number of special commands and keys in AutoIt that are represented by a combination of characters that themselves need to be escaped so that the interpreter doesn't get confused. To type the Alt key plus a letter, the letter A say, as a keyboard shortcut, you ask AutoIt to type !a (bang a). If the character you want to type is a bang/exclamation point on it's own, you need to surround it with curly braces {!}

One scenario where you might run into this is in entering user credentials where an account password might contain special characters like hashes and bangs. This is where a nice typing function comes in handy.

Function TypeCharacters([string]$Text) {

    $EscapeTheseCharacters = @('!', '#')

	$Text.ToCharArray() | ForEach-Object {
	
		$Character = $_
		
		If (($EscapeTheseCharacters | Where-Object { $_ -eq $Character}) -ne $null) {
			$Character = "{$Character}"
		}
		
		Send-AU3Key -Key $Character
	}
}

TypeCharacters('Hello!#')

We 'type' each character via AutoIt but check to make sure that we escape any of the special characters.