It would be great if we could cross-reference a course in our course catalogue with another course number. This way either (the original or the cross-referenced) course would satisfy a course requirement. This is especially handy for courses that are in the process of being retired.
For instance, lets say we have Alice enrolled in the 2010-2011 catalogue year. In that particular year she only needed 120 credits to graduate with a four year B.A. But she was required to take the course P146. She never took that course though for a few years.
The new catalogue year is set up as 2012-2013. In that catalogue year people are required to take 130 credits for the B.A., and instead of the course P146 they are required to take the course T146.
Now Alice can't take P146 because it is no longer offered, but instead needs to take T146, offered say in the fall of 2012. We don't want to modify the 2010-2011 catalogue year to change P146 to T146 bc some people in that degree in that year already have P146 (and still haven't graduated from the 2010-2011 start date). We also don't want to change the 2012-2013 catalogue year to include P146, since that is a retired course.
We could go through every degree & specialization and add a course group called 'P146 or T146', but this is a big pain, since this course occurs everywhere. We also have a number of other courses that also have this problem, so we would have to make a lot of course groups simply for courses that have been retired and be sure that is included in every catalogue year. Making modifying the degree & specialization course groups very cumbersome.
Instead, if we could modify a field in the course catalogue that says something to the effect of "This course is equivalent to _______", it would make our lives a lot easier, especially for those courses that were retired many years ago but still may be in use by returning students.
