What is an "Open Listing"?
Answers for Buyers

A homeowner who is also working along with an agent uses an “open listing”. This gives the agent the right to show the property to potential buyers. By using this type of listing the homeowner has the right to give this listing to as many agents as possible. When an agent sells your home for you, the agent earns commission for the sale.

Due to the way this type of listing works most agents won't market your home or enter it in to an MLS. Most agents will only do it if it fits the profile.