The best editor for programming will depend on the preferences and quirks of the user. Editors that can do syntax-dependent colouring of the text make it easier to read code and identify problems. xemacs and textpad are possible options.

.dxl files are script files used for customising Telelogic DOORS. they can be edited through notepad or any other text editor. It is suggested though that using a syntax editor such as Crimson Edit or Xemacs with a DXL syntax file applied is better, then you can get syntax highlighting for key words, etc which makes debugging much simpler