Changes to DSC Pull Server Configuration IDs

Has anyone tried to use the ConfigurationNames instead of the ConfigurationID (e.g. GUID)?
Not sure how to use the ConfigurationNames in the Pull server.
Reference:
http://blogs.msdn.com/b/powershell/archive/2015/05/29/how-to-register-a-node-with-a-dsc-pull-server.aspx?utm_content=bufferd9bce&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

The Configuration Name gets used as the MOF and checksum filename. Keep in mind you also have to set the shared secret, which is a change in the node LCM and in the web.config of the pull server.

My understanding of this feature is that DSC looks for RegistrationKeys.txt in the path specified in the web.config. Has anyone found out how this file should be formatted? A text file containing only the GUID does not appear to work in my lab.

I understand that the “ConfigurationNames” is a string array. So how does one manage the configurations based on this array of names?
What is the format of the shared secret?
It will be best if we could see a working example.