Sounds like this is related to the hoses, i.e., it's a place where the hose can be quickly connected or snapped in. See the following:

Increases Productivity
Easy To Use Interchange tools very quickly.
Chuck operates similarly to an air hose quick connection.(http://www.cleavelandtool.com/catalog/qctools.html)

There are no hose bibs allowed. You can put a quick connection or cam-lock fitting in the ground with a control valve and valve box "clearly labeled or painted purple." (http://www.pinellas-park.com/reclaimed/faq.html)

Hope it helps.

air couplers for quick connection and disconnection.

air couplers for quick connection and disconnection.

my opinion