The C stands for Control channel and every C or e (or X) is 20MHz bandwidth.
In case of Ceee and channel 5500:
5490-5570 used frequencies, where the control channel is frequency 5500.
In case of eCee and channel 5520:
5490-5570 used frequencies, where the control channel is frequency 5520.
A tool like inSSIDer will show exactely what is used in these cases.
In this topic you can find some more info:
http://forum.mikrotik.com/t/understanding-channel-width-options-and-limitations-due-to-country-registrations-plus-interface-vs-capsman-settings/151239/1