Finding a reference for square-rig sail terminology

What is the light-weather sail attached below a lower square sail, and where can its name be checked?

Consult an age-of-sail specialist and a detailed wooden-fighting-ship reference for the rigging terminology.

A viewer asks for the name of the light-weather sail that extends downward from a lower square sail. The question distinguishes it from sails set beside the main square sails and asks where the exact terminology can be checked. The answer directs the questioner to age-of-sail specialist Kate Jamieson and a detailed reference work on wooden fighting ships. The exchange points to the vocabulary and reference material needed to identify individual sails on a square-rigged warship.