MSQ > Maid Service Quote. It is the term associated with Maid Central Online Booking Tool.
When setting up your Quoting Tool, Include in MSQ from the Company > Quote Settings > Select Service Set to Manage > Availability the Include in MSQ check box must be marked in order for that service set type to display when using the internal quoting tool.
When setting up the External Quote Form for the Online Booking Tool, the Default Customer Source can be set to MSQ1 to indicate leads that are submitted/booked from the Online Booking Tool.
Company > Quote Settings > Select a Service Set to Manage > External Quote Form > Default Customer Source.