/etc/apache2/sysconfig/ directory, are regenerated automatically from information in /etc/sysconfig/apache2/ on Apache startup and so shouldn't be hand edited. See comments at the top of /etc/apache2/httpd.conf for more information.
This diagram is for SLES10 and Apache 2; similar arrangements were used with SLES 9 and Apache 1.3, with 'apache2' replaced by 'httpd' in filenames. In SLES 9 it was necessary to run SuSEconfig to regenerate the files based on sysconfig information.
2010-02-23: Debian diagram amended - the 'master' file was incorrectly labelled httpd.conf and should have been apache2.conf. Apart from anything else, you can't have httpd.conf including itself!