A purse of the C type is used to keep record of received credits.
A purse of the C type can be created only once and cannot be deleted.
WMC title units are actually promissory notes (obligations to transfer a respective number of WMZ title units by a certain date) to the creditors of the C type purse owner.
Number of units at WMC purse corresponds to a number of WMZ that must be transferred to creditors.
The C purse transaction history stores records of promissory notes issued to creditors.