We are using the Search/EquitySearch API and would like to understand the order of the results, this is an example of a search we are performing

The first result back is
"Identifier": "WISH.O",
followed by
"Identifier": "WISH.OQ", and then
"Identifier": "WISH.A",
It doesn't seem to be based on Alphabetical order, so we wondered if it was by primary listing, which in some of our other searches we don't believe it is.
Any information would be most appreacited.