IDL uses the following graphic characters:
" ' ( ) * , . / : ; | = [ \ ] { }
The { (left brace) and } (right brace) characters are national replacement set characters that may not be available on all keyboards. Wherever IDL specifies a left brace, the ??< trigraph may be substituted. Wherever IDL specifies a right brace, the ??> trigraph may be substituted.
Use of these trigraph sequences adds the following punctuation characters to the set in the preceding list:
< > ?