Project Planning Board: Indicator, Maintenance only allowed in Customizing

Dear All,

Can anybody put some light on custom only field in project planning board profile? when I pressed F1 help it gives following information

Indicator: Maintenance only allowed in Customizing

You use this indicator to specify that the planning board profile can only be changed in Customizing.

What kind of changes you can made in planning board other than customization? I checked this indicator and tried to change fields in planning board through CJ2B and it allowed. Even after unchecking the indicator also it allowed to change.