  The Rogers-Ramanujan identity for $\!\!\phantom{|}_1\psi_1$ $$
\sum_{n\in\mathbb{Z}} \frac{(a;q)_n}{(b;q)_n} z^n\;=\;
\frac{(q,b/a,az,q/az;q)_\infty}{(b,q/a,z,b/az;q)_\infty} $$ can be classified
as one related to the Bethe Ansatz for ``chain length $N=1$, ground state XXZ
model with an arbitrary negative spin''.
