I look this:

Note:
Extended property value support is only available through the Properties Window (Zoom dialog box) for custom user-specified properties as well as certain native ones such as CursorSchema and Value. For properties not supported, you can still specify values which are longer than 255 characters, or contain carriage returns and linefeeds by assigning them in code such as during the object's Init Event.


Where is the list of these privileged properties ?

I must write a program in order to discover them?

No good.

Fabio