For anyone who may be interested....
For most of my projects I use colour coding to visually distinguish a 'basic attribute' of an entity or fact within a model.
Example 1 - Modifying an existing (production) model.
Existing and unchanged: entity - black line, yellow fill; fact - black line work.
Proposed Modified: entity - dark blue line, pale blue fill; fact - dark blue line work.
Proposed New: entity - dark green line, pale green fill; fact - dark green line work.
Proposed Deleted: entity - red line, pink fill; fact - red line work.
Example 2 - Comparing two overlapping systems (eg one system provides data for another)
Common between both systems: entity - black line, yellow fill; fact - black line work.
System 1: entity - dark blue line, pale blue fill; fact - dark blue line work.
Change required to 1: entity - dark green line, pale green fill; fact - dark green line work.
System 2: entity - red line, pink fill; fact - red line work.
Change required to 2: entity - purple line, mauve fill; fact - purple line work.
....And a big red 'X' overstamped on items to be deleted.
cheers