Abel's identity for the dilogarithm (see the wikipedia page about polylogarithms) plays a role in web geometry as it is one of the abelian relations of the first example of exceptional web (Bol's 5-web) to appear in the literature.
I have heard it is important in other domains (cohomology of SL(3,C), algebraic K-theory, motives ). I would like to learn more about it.
I am asking for:
Insights on why Abel's identity is relevant in this or that field;
References where it plays a role.
Edit. I have just learned from this blog about Bridgeman's orthospectrum identity. Those interest in the question above might want to take a look at it.
