Calls can be nested. If a select attribute is encountered, it will evaluate that expression for a string that indicates the filename. If the string evaluates to empty, it will attempt to use the 'file' attribute as a default.
Filenames can be relative or absolute.
If they are relative, the base directory will be the same as the base directory for the output document. Close the given file and remove it from the formatter listener's table. Write the evalutation of the element children to the given file. Then close the file unless it was opened with the open extension element and is in the formatter listener's table. Copyright 2000 Apache XML Project.