- <listitem><para>Disable Immediate Configuration; This dangerous option disables some
- of APT's ordering code to cause it to make fewer dpkg calls. Doing
- so may be necessary on some extremely slow single user systems but
- is very dangerous and may cause package install scripts to fail or worse.
- Use at your own risk.</para></listitem>
+ <listitem><para>Defaults to on which will cause APT to install essential and important packages
+ as fast as possible in the install/upgrade operation. This is done to limit the effect of a failing
+ &dpkg; call: If this option is disabled APT does treat an important package in the same way as
+ an extra package: Between the unpacking of the important package A and his configuration can then
+ be many other unpack or configuration calls, e.g. for package B which has no relation to A, but
+ causes the dpkg call to fail (e.g. because maintainer script of package B generates an error) which results
+ in a system state in which package A is unpacked but unconfigured - each package depending on A is now no
+ longer guaranteed to work as their dependency on A is not longer satisfied. The immediate configuration marker
+ is also applied to all dependencies which can generate a problem if the dependencies e.g. form a circle
+ as a dependency with the immediate flag is comparable with a Pre-Dependency. So in theory it is possible
+ that APT encounters a situation in which it is unable to perform immediate configuration, errors out and
+ refers to this option so the user can deactivate the immediate configuration temporarily to be able to perform
+ an install/upgrade again. Note the use of the word "theory" here as this problem was only encountered by now
+ in real world a few times in non-stable distribution versions and was caused by wrong dependencies of the package
+ in question or by a system in an already broken state, so you should not blindly disable this option as
+ the mentioned scenario above is not the only problem immediate configuration can help to prevent in the first place.
+ Before a big operation like <literal>dist-upgrade</literal> is run with this option disabled it should be tried to
+ explicitly <literal>install</literal> the package APT is unable to configure immediately, but please make sure to
+ report your problem also to your distribution and to the APT team with the buglink below so they can work on
+ improving or correcting the upgrade process.</para></listitem>