dev1 & dev2 on localhost?

Server Config
1

What is the following code doing?

RewriteCond %{HTTP_HOST} ^(www.)?dev1.foobar.com$
RewriteRule ^(/)?$ projects/foobardev [L]
RewriteCond %{HTTP_HOST} ^(www.)?dev2.foobar.com$
RewriteRule ^(/)?$ projects/foobardev [L]
2

This reads to me as: if the host is dev1.foobar.com or dev2.foobar.com, then rewrite the root too projects/foobardev.