Index of notation/R

Expression	Status	Meanings	See also
$\mathbb{R}$	current	Real numbers
$\mathbb{R}_+$	dangerous	See $\mathbb{R}_+$ (notation) for details on why this is bad. It's a very ambiguous notation, use $\mathbb{R}_{\ge 0}$ or $\mathbb{R}_{>0}$ instead.	$\mathbb{R}_{\ge 0}$ $\mathbb{R}_{> 0}$
$\mathbb{R}_{\ge 0}$	recommended	$:=\{x\in\mathbb{R}\ \vert\ x\ge 0\}$, recommended over the dangerous notation of $\mathbb{R}_+$, see details there.	$\mathbb{R}_+$ $\mathbb{R}_{>0}$
$\mathbb{R}_{>0}$	recommended	$:=\{x\in\mathbb{R}\ \vert\ x>0$, recommended over the dangerous notation of $\mathbb{R}_+$, see details there.	$\mathbb{R}_+$ $\mathbb{R}_{\ge 0}$
$\mathbb{R}_{\le x},\ \mathbb{R}_{\ge x}$, so forth	recommended	Recommended notations for rays of the real line. See Denoting commonly used subsets of $\mathbb{R}$	$\mathbb{R}_+$