Treebore
First Post
I'm guessing that Black Ice Well was, like Paradigm Concepts' Unveiled Masters: the Essential Guide to Mind Flayers, begun before the finished SRD was released, and third-partty companies were all using the Gentleman's Agreement instead (for instance, St. Cuthbert is mentioned in Necromancer Games' The Wizard's Amulet).
Strictly speaking, some Product Identity terms could be technically used...but only because they slipped into the SRD by accident (e.g. "eladrin"). I suspect this is how Necromancer/Frog God Games is able to have monsters like the Slaad Lord of Entropy and the Slaad Lord of the Insane in their Tome of Horrors books (though I may be wrong).
I remember Clark Peterson stating he had direct permission from WOTC to use several IP creatures in Tome of Horrors I.