Unfortunately, it depends on where you order from.  Golf Galaxy lets use all kinds of characters, but on Dickssporting Goods site you can't use any special characters at all.  Dicks does have free shipping though.

I believe you are only allowed to use commas, period, and quotation marks if I am not mistaken. 

I went to Golf Galaxy last year and they wouldn't let me get all 7's even though I'd done it before the year before.  Those big box stores just don't have knowledgable staff members or the customer service that pro shops do. Just go to your favorite course or club and order them there. If it's something that Titleist won't let you do then you're out of luck, but at least you know that they'll give it a shot  

I just placed my order and used @ hopefully i dont get rejected.