This is sort of right but not really.
eCPM is actually Effective CPM (Cost Per Thousand Impressions). This is basically a term used when a network is offering a rev-share based on impressions. You are right that sometimes it can include Clicks (CPC) mixed in there and backed out to an effective CPM, but not always. CPM is moreso used when you are being paid a fixed CPM rate for your traffic. eCPM is typically the default method used with most ad networks (and often times the only option). Fixed CPM is typically something you'll have to negotiate with a network. Many are unwilling to give this out of the gate on untested traffic, and it may take a long time of building trust to get it, or they might try and low ball you on the rate. Sometimes it can be better to take an eCPM as long as you are backing out to a fair rate, and you are getting a decent rev-share %
Hope this helps.
