IMS Common Cartridge. IMSCC is a two-part acronym. IMS stands for IMS Global Consortium (the original name was the Instructional Management Systems [IMS] project). CC stands for Common Cartridge, which is the standard to which we design our course exports for maximum compatibility with the widest possible variety of LMSes.
When we at NROC refer to IMSCC, or the IMSCC version of a course, we are talking about the file used to install the course in your institution's LMS.