Li (禮) is a Confucian virtue commonly translated as propriety or proper ritual. Diamond equates it terms loosely with an endum*. Li is one of the four Cardinal Virtues of the Confucian philosopher Mencius (孟子), and Diamond’s discussions about it are often in the context of one or more of the three other such virtues, Jen*, Zhi*, and Yi*. See Four Cardinal Virtues of Mencius*.
Timeline: 2010 on. Note that Diamond originally regarded Li as the equivalent of Cantillation*, a role that was later assigned to another of the Cardinal Virtues, Yi, in 2015. The subsequent “endum” role for Li was developed in 2018.