[ossec-list] How to create custom parameter in ossec.conf e.g client_id

[d***@gmail.com]

How i can create custom parameter in ossec.conf file. Let say client_id
<localfile>
<log_format>command</log_format>
<client_id>1011</client_id>
<command>df -P</command>
</localfile>

this is sample ossec.conf code.
i have added client_id customely. But dont know how i can access it in the
terminal logs.

Output sample:
Date: ossec-logcollector: Info: Monitoring full output of
command(360):(client_id): df -p