There seems to be a little confusion over the differences between identity systems and meta identity systems. Some identirati are of the opinion that in order to qualify for the “meta” tag it suffices to support a single family of protocols and multiple token formats, while others are convinced that a “meta” system should also support multiple protocols.
Since this seems confusing to me, I implicitly suggested to call the later an “identity meta-meta-system”. Opening this can of worms, you can easily derive at an “identity meta-meta-meta-system” etc. to include other staggering advances in interoperability such as semantics.
To prevent this kind of meta proliferation, I am now convinced that we should define the goal of “getting-these-pesky-identity-thingies-to-work-with-each-other”: Aleph0 Identity System (AIS) . The AIS can – by definition – not be implemented, but describes the elysian state, where all identity systems that would like to be interoperable or interchangeable, are interoperable or interchangeable with all others participating in the Aleph0 Identity System.
 This is motivated by the notion that the cardinality of a countable set (in this case the meta’s) is commonly denoted by Aleph 0: