between VAT and Property Class?
2)Named visual attributes define only font, color, and pattern attributes; property classes can contain these and any other properties. You can change the appearance of objects at runtime by changing the named visual attribute programmatically; property class assignment cannot be changed programmatically. When an object is inheriting from both a property class and a named visual attribute, the named visual attribute settings take precedence, and any visual attribute properties in the class are ignored.