Control characters RS and US (Left ALT-030 and Left ALT-031) are not only invisible, but are also at the top of the alphabetical order. This means that each of those characters when inserted before any name in Revit will move this name to the top of any alphabetically sorted list of names without changing the name. This allows creating custom orders of any list of names in Revit like Worksets, View Types, View Templates, Views, Line Styles, etc.
The above control characters can also be inserted using a contextual menu revealed with right-click in any textual field. This is often more convenient than typing the “Left ALT-“combinations, especially on some laptops, which cannot even simulate the numeric keypad.
Left ALT-030 is before Left ALT-031 in the alphabetical order and the number of those characters inserted before a name matters in such way that the names preceded by more characters are placed higher on the list. A good example of this approach is a list of Line Styles, in which we would like to place our standard Line Styles with company prefix at the top and achieve the result shown below: