A set of configuration template files is structured as follows, assuming that the root folder is default/ or custom/. Editing these files changes the Apache configuration.

Root templates are starting points in generating configuration files. Plesk always starts generating a configuration from one of these files. All root templates contain statements that include the other templates located in respective folders (domain, server and service).        
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atmail.php     Root template of a server-wide configuration for Atmail Light.
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atmailcom.php     Root template of a server-wide configuration for Atmail Full.
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domainForwarding.php     Root template of a per-website configuration for websites with forwarding, either standard or frame.
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domainVhost.php     Root template of a per-website configuration for hosted websites.
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domainWebmail.php     Root template of a per-website configuration for a webmail service.
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horde.php     Root template of a server-wide configuration for Horde.
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server.php     Root template of a server-wide configuration for server services, such as Tomcat, Mailman and several others. For details, see the contents of the server/ directory below.
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nginx.php     (In Plesk 11.0+) This template includes the server-wide configuration of nginx.
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domain/     Contains templates included in a per-website configuration.
 
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domainVirtualHost.php   Configuration for hosted website addressed by domain name.
 
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frameForwarding.php   Configuration for website with frame forwarding.
 
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nginxDomainVirtualHost.php   (In Plesk 11.0+) This template includes per-website configuration of nginx.
 
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standardForwarding.php   Configuration for website with standard forwarding.
 
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subDomainVirtualHost.php   Configuration for hosted website addressed by subdomain name.
 
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service/   Contains templates of configuration for website services included in a website configuration.
   
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bandWidth.php Configuration for website bandwidth limits.
   
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errordocs.php Configuration for website error documents.
   
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protectedDirectories.php Configuration for password-protected website directories.
   
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tomcat.php Configuration for the Tomcat service on a website.
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server/     Contains templates included in a server-wide configuration.
 
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PCI_compliance.php   Defines directives specific to meeting PCI compliance.
 
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mailman.php   Configuration for the Mailman service.
 
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nameVirtualHost.php   Defines NameVirtualHost directive.
 
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tomcat.php   Configuration of the Tomcat service.
 
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vhosts.php   Configuration for the server default virtual host (a virtual host addressed if a request is made to an IP address registered in Plesk but no default website is assigned to it).
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service/     Contains context-free templates of configuration for various services.
 
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asp.php   Configuration for ASP.
 
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mod_fastcgi.php   Configuration for FastCGI.
 
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mod_perl.php   Configuration for Perl.
 
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mod_python.php   Configuration for Python.
 
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php.php   Configuration for PHP.
 
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php_over_cgi.php   Configuration for PHP over CGI.
 
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php_over_fastcgi.php   Configuration for PHP over FastCGI.