Walls are used to surround a comment as top, bottom and sidelines. They are used to structure the source code and are removed when the source code is parsed. 

Doc-O-Matic removes top and bottom lines that consist of same characters. Sidelines are removed if they consist of identical strings of characters. If you use different characters for top, bottom and sidelines, you must separate lines from other wall lines by at least one white space. You have to insert at least one white space between comment text and walls. 

Default wall characters are "#$%&'*+-/=@[\]^_`{|}~. Parsing the source code Doc-O-Matic removes first top and bottom lines and then side lines of walls in a comment.