What is the name of this single slot PCB-mounted connector?
21 Position Connector Receptacle, Outer Shroud Contacts


https://www.digikey.ie/product-detail/en/amphenol-icc-fci/91930-21121LF/609-1591-ND/1001905

From Jasen's comment and datasheet:  


  datasheet note 7 "the three slots may be located at either end"