the base station site for fully manual mechanical adjustments. Increasingly, antenna subsystems offered electro-mechanical and then fully electronic adjustment, which allowed remote control of these adjustment mechanisms. This remote control was utilized in a fairly slow, static, and semi-static human-scale work- flow control loop latency mode, though it did provide the initial transition from a horizontal 2D-centric to a more 3D-centric (azimuth + elevation) way of thinking about and operating antenna boresight directional tuning. While antenna and base station vendors had their own ways of effecting these adjust- ments, a specification and standard was made available from the Antenna Interface Stan- dards Group (AISG) that enjoyed and still enjoys significant market uptake. The AISG standard includes, among other features, support for antennas with remote electrical tilt for vertical/elevation adjustment. AISG has become and remains part of the 3GPP spec- ification by way of reference within 3GPP TS 25.802 "Remote control of electrical tilting antennas," 3GPP TS 25.460 "UTRAN luant interface: General aspects and principles," 3GPP TS 25.461 "UTRAN luant interface: Layer 1," 3GPP TS 25.462 "UTRAN luant interface: Signaling transport," and 3GPP 25.463 "Tilting (RET) antennas Application Part (RETAP) signaling." These have further been transferred to the 37-series TS (3GPP TS 37.460, 37.461, 37.462, 37.466) to reflect the fact that the Iuant interface is now applicable to 5G NG-RAN, 4.1 Introduction not just Universal Terrestrial Radio Access Network (UTRAN). Furthermore, AISG v3.0 itself was released in late 2018. 4.1.3.2 New 5G Era: Where We Are While AISG specs will continue to be referenced, provide value, and undergo evolution, newer antenna interface specifications have come to the fore due much to needing improved support for new capabilities associated with historical transitions nascent in the pre-5G, LTE era including: From 2D to 3D tunable directional radiation patterns; From a "static directional antenn