pdaAttributeTypeAttributes are key/value pairs to annotate building blocks and views with information that is likely to be software specific. So it is more a 'flag' then a value. The value is just a string and not something with an expression in it.
StructureThis element does not have elements. The attributes are shown below, in a sorted per type fashion.
<pdaAttributeType key="..." ... > ... </pdaAttributeType>
XSD The schema file can be downloaded or viewed at xPDK_Base.