 programs can write to both <tt>stdout</tt>
and <tt>stderr</tt> without timing restrictions.  So role
protocols that use both <tt>FCGI_STDOUT</tt> and <tt>FCGI_STDERR</tt>
allow these two streams to be interleaved.<p>

All role protocols use the <tt>FCGI_STDERR</tt> stream just the way
<tt>stderr</tt> is used in conventional applications programming: to
report application-level errors in an intelligible way.  Use of the
<tt>FCGI_STDERR</tt> stream is always optional.  If an application has
no errors to repo