This is known as a USB Accessory Charging Adapter of which a dock is one form but the old Battery Charging standard also anticipated it being in the form of a c

This is known as a USB Accessory Charging Adapter of which a dock is one form but the old Battery Charging standard also anticipated it being in the form of a cabled adapter: Battery Charging 1.2: > An Accessory Charger Adaptor (ACA) is an adaptor which allows a single USB port to be attached to both a charger and another device at the same time. Figure 3-1 shows the various configurations covered. The third one indicates the intent of having an adapter with data pass through to an accessory while powering from a third port fed by an external USB supply. These exist today as USB-C splitters.