It comes as no surprise that designers, artists and agencies alike all have their own specific ways of setting up a document. Previous versions of popular page layout programs made it difficult to have your agency information (also referred to as a slug or bug line) included in a document. The slug is important to each specific file because it lists things like agency info, sizes colours and fonts used, and versioning info. If a designer wanted to print a proof showing the trim marks and the slug, the document size set in your page layout program had to be larger than the final trim size of the actual printed piece to include this info. This made it horribly difficult for prepress departments and usually causes some confusion when processing files because a final file is processed at the final document size.
In the latest versions of the Adobe line of products, when setting up a document you can specify the trim size, the bleed allowances and now the slug area. Typical allowances would be .125″ on all sides for the bleed. The slug area is usually at the bottom of the document and 2-3″ is usually suffice.
If you input these details when you are opening a new document, everyone wins. By properly setting up your document specifications right from the start, you can effectively communicate the specifications to the departments that will be handling the files after you.