There are two ways for a course to be identified:
The old way
So : 0657.201Y
06 = School of Computing and Mathmatical Sciences 57 = Department of Computer Science 2 = Second year paper Y = Full year paper.
Papers are most often refered to by their final 3 digit code, eg, 201, 312, 103 etc etc.
The problem with this is that it assumes you know what school and department the paper is under. Normally WLUG members will be refering to Computer Science !
Semesters can be A - First Semester, B - Second Semester, Y - Full year, S - Summer School (there are other semester codes, but they are not commonly used).
The new way (starting from 2003) has been simplified (must have confused the management students !)
The School and Department have been scrapped, and replaced with a 4 letter code
eg 0657.201Y now changes to COMP201Y