subdomain directory

[ToolBox]

If i made 1stleveldomain.com , the directories for this domain created to

/var/www/vhosts/1stleveldomain.com/

#ls /var/www/vhosts/1stleveldomain.com/
anon_ftp conf etc lib private tmp web_users
bin dev httpdocs lib64 statistics usr
cgi-bin error_docs pd subdomains var


if i made subdomain named office and its root dir for httpddocs.office

#ls /var/www/vhosts/1stleveldomain.com/
anon_ftp conf etc lib private tmp web_users
bin dev httpdocs lib64 statistics usr
cgi-bin error_docs httpdocs.office pd subdomains var


The httpdocs.office directory created.

but /var/www/vhosts/office.1stleveldomain.com/ was created and inside this directory was

#ls /var/www/vhosts/office.1stleveldomain.com/
anon_ftp conf error_docs etc pd private statistics subdomains web_users


Is this ok or is it a bug?

The directory named subdomain (/var/www/vhosts/1stleveldomain.com/subdomain/ and /var/www/vhosts/office.1stleveldomain.com/subdomain/) is there to do what?

The document directory of subdomain (like /var/www/vhosts/1stleveldomain.com/httpdocs.office）,
why does not in the subdomains directory(like /var/www/vhosts/office/1stleveldomain.com/)?

Where is The subdomains cgi-bin directory?

Plesk10.4.4 subdomains works could not understand...

Someone Please explain.