+
+ The direct sum of $V$ and $W$ is $\directsum{V}{W}$, of course,
+ but what if $W = V^{\perp}$? Then we wish to indicate that fact by
+ writing $\directsumperp{V}{W}$. That operator should survive a
+ display equation, too:
+ %
+ \begin{align*}
+ Z = \directsumperp{V}{W}\\
+ \oplus\oplusperp\oplus\oplusperp
+ \end{align*}
+ %
+ Its form should also survive in different font sizes...
+ \Large
+ \begin{align*}
+ Z = \directsumperp{V}{W}\\
+ \oplus\oplusperp\oplus\oplusperp
+ \end{align*}
+ \Huge
+ \begin{align*}
+ Z = \directsumperp{V}{W}\\
+ \oplus\oplusperp\oplus\oplusperp
+ \end{align*}
+ \normalsize