DOCBOOK-APPS: Including output of a command?

[Rory Hunter]

Hi,

I don't suppose it's possible to include the output of a system command in 
a docment somehow, i.e. with some hackery like,

<!ENTITY date CMD "date +%A %e %B">

or an equivalent? Obviously competely unportable, but it'd be quite nifty.

-- 
roryh