The suffix "xxx" is the factory programmed configuration code that is programmed in the device when they are shipped. This is a file specific to a particular set of frequency outputs with respect to a reference determining the configuration as per customer's requirement that we use to program the device. So the "xxx" is usually replaced by numbers resulting into part numbers such as CY2907SC-131, CY2907SL-262 and CY2907SC-367 for example that will have the respective devices output different frequencies with respect to the Reference. The "131, 262 and 367? are the three digit dash codes that are assigned to the factory programmed orders by customers. The dash code is a serial number, a unique number that is assigned to the configuration requirement used to program the device. So different dash codes will have different frequencies output by the device that are possible.