rics for overnight index swap

Hi Everyone

I am trying to source RICs of overnight index swap - for example USDOIS= or 1#USDOIS=, I get a lot of RICs like USD1MOIS, USD3MOIS, but the max tenor is 2Y.

I'd like to find the tenor which is more than 2 years, then I find the ric "USD5YOIS=TREU", the fieldlist of "USD5YOIS=TREU" is quite different with the fieldlist of "USD1MOIS", does anyone can explain a little bit?

Thanks

Chris