In my opinion, the "OPDS" part can be left out completely. If there were 2 different types of catalogs available in e-readers, then yes, specifying "OPDS" would be useful. But because there is only one type, OPDS, why state it explicitly, when the general public has no idea what OPDS is, anyway? Calling it "OPDS" has zero informational value, but it has quite high potential "confusing" value.
This also happened in the
Facebook Stanza group -- when I mentioned that Marvin, too, now offers OPDS catalogs, long-time Stanza users asked me "what the hell is that?"... even though they've been using OPDS catalogs in Stanza for years.
In fact, Stanza is the model of user-friendliness in this regard. Stanza offers the menu button
Get Books. (Could the button label be any clearer?) And after you go there, the very first button says,
Catalog. And under that button are all the OPDS catalogs, but it's really not necessary to call them that.