In a CAD system, dimensions are entered as an arithmetic combination of quantities expressed in both English and metric units. The system converts the units and combines the quantities to produce the dimension. Also, an undo tool stores undo information in nonvolatile storage, so that drawing operations may be undone at any subsequent time, even after a file has been saved and retrieved, or transferred to another user. The system also associates drawn content with a paper size and orientation, rather than a specific printer, and associates each paper size and type with a printer, so that when printing a page, the paper size and type associated therewith can be used to select a printer. In this way, content may be printed on an appropriate printer based upon a paper size and orientation, without storing printer selections or details in the file.