Matrices

$M_{n,m}(X)$	$n\times m$-matrices over $X$
$M_n(X)$	$M_{n,n}(X)$
$M_{n,m}$	$M_{n,m}({\mathbb{C}})$
$M_n$	$M_{n,n}$
${\mathbb{M}}_{n,m}(X)$	the operator space of $n\times m$-matrices over $X$
${\mathbb{M}}_n(X)$	${\mathbb{M}}_{n,n}(X)$
${\mathbb{M}}_{n,m}$	${\mathbb{M}}_{n,m}({\mathbb{C}})$
${\mathbb{M}}_n$	${\mathbb{M}}_{n,n}$
$C_n(X)$	${\mathbb{M}}_{n,1}(X)$, the columns of an operator space
$R_n(X)$	${\mathbb{M}}_{1,n}(X)$, the rows of an operator space