A relational symbol denoting a curly preorder or precedence relation that combines aspects of \prec and \leq in ordered sets.
Examples
Partial order relation in lattice theory
a \preccurlyeq b \text{ and } b \preccurlyeq c \implies a \preccurlyeq c
Comparing elements in a poset
x \preccurlyeq y \preccurlyeq z
Subset relation with additional structure
A \preccurlyeq B \text{ in the lattice } (\mathcal{P}(X), \preccurlyeq)