Arnor,
To control the paragraph format with an attribute, use format rules in the EDD rather than read/write rules. You can not copy an attribute value to a property value, but can test for specific attribute values and set a property accordingly. For example, if you have an attribute named Widow and are sure the value will never exceed 10, you can tediously have a rule such as:
1. If context is: [Widow = "1"]
Pagination properties
Widow/orphan lines: 1
Else, if context is [Widow = "2"]
Pagination properties
Widow/orphan lines: 2
...
Else, if context is [Widow = "10"]
Pagination properties
Widow/orphan lines: 10
For other paragraph pagination properties, your EDD also needs to test for possible values, for example:
2. If context is [Placement = "RunIn"]
Pagination properties
Placement: Run-in head
Default punctuation: .
Else, if [Placement = "Side"]
Placement: Side head
Of course, the attribute names can be quite different from FrameMaker's property names or value keywords.
--Lynne