oracle client for siebel server configuration

Hi ,

To install siebel as prerequisite we are installing oracle client on the siebel server machine. Our client is providing ldap.ora instead of tnsnames.ora file. Through out my earlier projects we used to have tnsnames.ora entry which is having connection details of database. CAn you Please confirm instead of having tnsnames.ora , can we use ldap .ora which is having Db server details in it. Have you ever seen other clients using this way without tnsnames.ora for siebel installation.

Can you please provide any documentation which confirms that we must need tnsnames.ora, not ldap.ora.

Thanks much in advance.