I am interested in a certain class of directed hypergraphs, more precisely in the class of those hypergraphs each of whose hyperedges contain an even number of nodes (not necessarily the same even number for each hyperedge!), the half of which are "initial nodes" and the other half being "terminal nodes".
This is admittedly a strong condition, but at least directed graphs are a special case of hypergraphs with said property. Has this class already been studied? Does it have a name?