The uses for DXL attributes are enormous. They range from showing the specific content from links, or multiple links, or multiple hops through links, calculated values, filtered values etc.
Layout DXL can be easily generated by a user with the inbuilt traceability wizards. Primarily for performance reasons, Layout DXL should always be converted to a DXL attribute (again using the DOORS inbuilt functionality). But there are other advantages:
Although the code of a DXL attribute can exist within a module it is more commonly referenced to an external include file. This has the significant advantage of reuse. If a script is located in the addins folder then once that file is modified the changes are instantly propagated to all modules that use this attribute ensuring consistent use across the project. Of course, you only have to make a single modification.
You can even have a single include file with all the required functions embedded within it.
For example:
This has the advantage that common functions for displaying text from buffers are all in one place.
The DXL attribute then consists of an include to this file and then a call to the appropriate function.