Visibilty & Interactivity defaults

All,

What are the defaults for the Visibility and Interactivity attributes
when they are not present in the CGM?

The AppStructure-interactivity test suggest that all APS have 
an Interactivity attribute even though there is no APS ATTRIBUTE 
of type "interactivity" in the CGM as is the case for 
AppStructure-interactivity.cgm

The AppStructure-visibility test suggest that APS do NOT have a
"visibility" attribute when no APS ATTRIBUTE of type "visibility" 
is present in the CGM.

Can anyone clarify this for me.

Regards, 
Don.