W/kg : Watts per kilogram
BikePower-to-weight ratio: the number that predicts climbing performance better than raw FTP alone.
A 70 kg cyclist with a 280 W FTP has a 4.0 W/kg ratio. That ratio : not raw watts : determines climbing speed (> 4 W/kg = good climber, > 5 W/kg = amateur elite). In long-distance triathlon, where climbs are long and moderate, a ratio of 2.8-3.5 W/kg covers the vast majority of competitive athletes.
In TriPaced:
In TriPaced, W/kg is shown in your fitness profile (FTP ÷ body weight from Settings). The engine uses it to calibrate target TSS for long bike sessions based on the climbing profile declared in your race settings.
Source Allen, Coggan & McGregor, Training and Racing with a Power Meter (3rd ed., 2019) - Chapter 3, Power Profile & W/kg categorisation