GC510P setup Voip using YealinkW60P/W56H

When reading the User Manual for the subject Auto-VoIP the procedure to enable a port for Auto-VoIP is easy.

I connected my Yealink-base to port 2.

On page 119 I read:"From the Class Value menu, specify the CoS tag value to be reassigned for packets
received on the voice VLAN when Remark CoS is enabled."

The manual does not explain the meaning of the Class Value (default=7). Can I leave this value unchanged?