A node or link rule (data rule) consists of an object type and
attribute conditions followed by declarations.
A data rule is defined on a group of data
model objects belonging to the same class, or having a common
ascendant class, or belonging to the same user-defined type. It is
applied to the graphic objects used to visualize the data model
objects in the diagram.
In the Designer, you see the data rules
(node and link) in the upper left pane, titled Style Rules,
following the Options. This pane shows a hierarchical view of the
rules depending on how specific they are.
In the Designer, you see the declarations in
terms of property values in the Styling Customizer or the optional
list of Styling Properties.