You have appeared to have reverse engineered the meaning of the asterisk. Since I guess you have no source for the design time component code you'll need to rely on such reverse engineering, or any documentation that you can find.
In the comments you wonder how the component could cause the Object Inspector to display the asterisk. In order to do so the component would register a property editor that overrides TPropertyEditor.GetName
. By doing so it can return any name it fancies and the Object Inspector will faithfully display that name.
To illustrate I've taken one of my own property editors, and hacked it around like so:
type
TMinMaxGridColumnProperty = class(TFloatProperty)
public
function GetName: string; override;
....
end;
function TMinMaxGridColumnProperty.GetName: string;
begin
Result := inherited GetName + '*';
end;
And now the properties that are served by this property editor appear like this in the Object Inspector:
So it seems almost certain to me that this is how the component you are working with is effecting this. The design time code will use the state of the component to determine whether or not to append the asterisk.