Every carrier is different but generally it means that you have some catastrophic coverage for things like cancer, transplants and HIV/Aids etc. Usually there are exclusions which your employer sets in place and usually your policy is limited to a specific dollar amount of coverage at which time you are no longer able to be covered (policy limit). Read your benefit package or check with your HR department for specific clarification. I used to work for Blue Cross and Blue Shield and later I became a Certified Professional Medical Coder. That was back in the good days before I became disabled. Hope this helps.