An external stylesheet is considered a stylesheet which exists as a seperate file from the (x)html document which it is associated with. Stylesheets can also be considered embedded stylesheets, in which the stylesheet is embedded in the acutual (x)html document in which it's used.

Both types of stylesheets have their advantages and disadvantages. External stylesheets have the advantage of modularizing the different types of documents, and the ability to use the external stylesheets in more than one (x)html document. The disadvantage of external stylesheets is that the author must always insure that the external stylesheet is where the (x)html documents expect it to be. In Xport, this means that external stylesheets must always accompany any reports that need them.