Do the terms "quiver" and "meta graph" refer to the same concept? Do the terms "quiver" and "metagraph" refer to the same concept?  Or is there a distinction I am missing.
My sources are 


*

*Quiver - http://ncatlab.org/nlab/show/quiver

*Metagraph - http://www.proofwiki.org/wiki/Definition:Metagraph

From Wikipedia: "a quiver is a directed graph where loops and multiple arrows between two vertices are allowed, i.e. a multidigraph". Any talk about quivers I've heard starts by explaining that they are just another way of viewing (a general type of) graphs, but that the focus of interest is different from that of graph theorists, whence the different terminology. However I've never heard of a metagraph before, and from the link you provided (which is not very clear) you cannot use a metagraph in place of a quiver (or of a graph), because you apparently are not even allowed to consider its set of vertices (called objects). This is not so much because they might be too numerous to be a set (like when they would form a set-theoretic proper class), but because the theory in question is not founded in set theory in the first place.
