A document icon should help the user understand what kind of data is stored in that document icon and what application is associated with the document. Figure 4-14shows a number of document icons used in the desktop that you can use as templates when designing your own document icons.
Applications that support multiple file formats need different document icons for the different output formats. Rather than creating a distinctively different graphic for each format, you might use the same graphic for the basic file and add a "tag" to delineate the format.
In the case of the document icon, the basic rectangle of the document is left- aligned in the icon square. If the tag approach is used, place the tag on the right side of the icon, half on and half off the basic icon, but not obliterating the descriptive graphic, as illustrated in Figure 4-14.