I am writing a research paper, and I would like to somehow denote the set of relational operators
$$ \left\{ =,>,<,\leq,\geq,\neq\right\} $$
Before I use some random symbol for that purpose, such as
$$ \Theta:=\left\{ =,>,<,\leq,\geq,\neq\right\} $$
so that then I can write expressions like ...$\forall\sigma\in\Theta$..., I would like to ask if a standard notation for that set exists.
I have searched Google and did not find an answer to the question; also, I don't remember seeing this in a book.