Core courses are the required courses within a degree or certificate and must be completed with a grade of "C" or better.
These are courses required for all students.
Compulsory courses required for the completion of one's degree.
Compulsory courses required for completion of the degree.
The courses required in your major.
No, they are not courses with a hole in them but those courses needed to complete the basic academic component required of all students for graduation. Again, each college has its own core.
Mandatory courses required for completion of a degree.