As with the application icon, it's OK to use your company identification in a document icon. Be sure not to change the shape of the document icon unless the document that your application creates is fundamentally different from most documents. One example of a document that is fundamentally different is a stack. The stack icon is a metaphor that represents a stack of cards, similar to a stack of index cards that you might use to store notes or related information. Figure 8-35 shows some examples of custom document icons that show the range of acceptable and unacceptable customizations.
Several conventions exist for conveying document types.
You can use these visual clues or others that have meaning for your documents' contents. Documents that are text-only or primarily text use broken lines on the document page. Page layout documents typically include a filled rectangle and broken lines to indicate that the document contains text and pictures. Graphics document icons use geometric shapes or other graphics or graphics tools such as paintbrushes. The standard representation for a file of type 'PICT' is a circle, a square, and a triangle.