Definition:Ordering/Notation

Definition
Symbols used to denote a general ordering relation are usually variants on $\preceq$, $\le$ and so on.

On, to denote a general ordering relation it is recommended to use $\preceq$ and its variants:
 * $\preccurlyeq$
 * $\curlyeqprec$

To denote the conventional ordering relation in the context of numbers, the symbol $\le$ is to be used, or its variants:
 * $\leqslant$
 * $\leqq$
 * $\eqslantless$

The symbol $\subseteq$ is universally reserved for the subset relation.

If, for two elements $a, b \in S$, it is not the case that $a \preceq b$, then the symbols $a \npreceq b$ and $b \nsucceq a$ can be used.

When the symbols $\le$ and its variants are used, it is common to interpret them as follows: