It's a relative bearing off of north or south. ie N 45 degrees 0 minutes 0 seconds W would be northwest. N 45 degrees E is northeast. N 135 degrees W would be southwest. N 135 degrees E is southeast. The points would reverse if the notation were S 45 E = southeast. The only place I have seen this notation used is from surveyors or people such as contractors and property deeds that work from their information.