Before you can edit or analyze an existing feature or features with
the Digitizer tool, you first must select
them with the Digitizer tool active. Once a feature is selected, you can
tell that it is selected because it will be drawn with a different style.
The different methods for actually selecting features are described here.
Below are the sub-menu Advanced Selection
Options available in the Digitizer right-click menu. The options
available will depend on if no features, or if a feature of a certain
type (point, line or area) are selected at the time of right-click.