Could someone help me to understand the sentence below?
The trademarks, logos, and service marks displayed on the Site are registered and unregistered Trademarks of the Massachusetts Institute of Technology (MIT), European Research Consortium for Informatics and Mathematics (ERCIM), or Keio University (Keio).
I understand the "trademarks, logos, and service marks" are registered. However, I do not get why a word "unregistered" comes right after "registered."
Does it mean "trademarks of MIT, ERCIM, Keio" are not registered?
Is "registered and unregistered" a kind of idioms? I have seen this a lot in some websites.
I think it just means that some have been rigistered but others haven't, though they don't want people using them without permission evern when unregistered.