at was added to the CORBA specification
to avoid race conditions for servant deletion in threaded servers. <a href="ftp://ftp.omg.org/pub/docs/orbos/98-07-12.pdf">ftp://ftp.omg.org/pub/docs/orbos/98-07-12.pdf</a>
contains the relevant text. Check <a href="../poa_migration.html#Reference counting Servants">here</a>
on some hints to avoid trouble. From TAO 1.4.6 reference counting is always
enabled for servants and RefCountServantBase is a noop struct you don't
need anymore.</li>

<li>
The POA now supports ac