that would be proximity-hosting. Colocation for financial order submission or data retrieval is generally on the premises of the exchange, ECN,...
Quote from vincegata:
Colocation is a tech term which means a practice of housing servers in a datacenter to take advantage of infrastructure, bandwidth, latency, security, etc. E.g. it's used for web-hosting, not just financial apps. In finance it's usually means hosting server in a datacenter close to exchange.