Site-to-site transport interlock

From Memory Alpha, the free Star Trek reference

The site-to-site transport interlock is a component of the transporter system, designed to permit site-to-site transport. Deactivating the interlocks limits beaming down to transporter pads.

In 2367, Miles O'Brien deactivated the interlocks in an attempt to thwart Commander Data, who had seized control of the USS Enterprise-D and taken it to Terlina III. The attempt failed, as Data used a series of force field commands to reach Transporter Room 1 and reactivate the interlocks. (TNG: "Brothers")