Can the Apach AuthLDAPNURL be pointed at the root of a tree?

I have a server where I need to use Apaches AuthLDAPNURL value, but I cannot start at any specific O, OU, or DC. For whatever reason this tree has everybody in 19 Organization (O) objects, hanging off the root of the tree. Not my choice in LDAP tree design, but so be it.

The format should be: AuthLDAPDNURL "ldaps://myserver.com:636/o=someO???(objectClass=user)"

Where right after the :636/ is the base DN to start searching from.

Can I leave it blank, and request subtree searching from the root of the tree as follows:

AuthLDAPDNURL "ldaps://myServer.com:636/??sub?(objectClass=user)"