Special case of include file are files named These files will always be included in search, even if there is no Include section defined in WBSP file. WBSP engine will try to read file located in same directory with WBSP file and, if that file does not exist or does not contain specified variable, it will proceed reading all files located in directories above current directory until wwwroot directory of virtual host is reached.  However, none of the files will be processed if WBSP engine finds the variable either in WBSP file itself or in other include files.