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.