Which crypto exchange does Alpaca route to?

The documentation says:

Alpaca provides crypto data from multiple venues and does not route orders to all venues even though it offers data.

I’d like some clarification on this. Let’s say I do a market buy - which exchange does it get routed to? (There’s no point in me pulling quotes for an exchange I won’t execute on!)

Thanks.

edit:\ Think I found it. From here:

Returns the XBBO for a crypto symbol that calculates the Best Bid and Offer across multiple exchanges. If exchanges is not specified then only the exchanges that can be traded on Alpaca are included in the calculation.

These are stated to be ERSX,GNSS.