What is meant by the notation $\tau_1\prec\tau_2?$

Question

Let $\tau_1,\tau_2$ be two topologies on a set $X.$ What is meant by the notation $\tau_1\prec\tau_2?$ Does it simply mean $\tau_1\subset\tau_2?$

Answer 1

Yes. Sets can be partially ordered according to the relation

$$A \preccurlyeq B \Leftrightarrow A \subseteq B$$