Logical/Implementation
(Both System and System Interaction)
uNot Designer-like Logic/Physical
uSpecify logical rules at the logical level
ØONLY additional rules at Physical level
uFor example, in data model
ØLogical -- Class, attribute, association
ØPhysical – Generation algorithm, schema organization. 
§NOT Table, column names
uRules are the system – mostly
“The articulation of the rules is
independent of the
implementation of the rules.”