A roadmap when planned may contain a set of features that are either blocked by other features (depend on the release of some features) or block other features (depends on the release of itself for further feature enhancements).
All these features that either block or are blocked by are dependent features. When planning the prioritization of features, the dependency as information is required to plan effectively and understand blockers as per the importance.
In the zeda.io roadmap, you can effectively mark a feature as a dependent (feature A {blocks/ is blocked by} feature B). This information is visually available on the roadmap in the timeline view across a feature as an indicator of the total number of dependent features.
When clicked on the number near the feature:
For all co-dependent features present in the timeline view, arrows show the presence on the roadmap as when they are planned
For all co-dependent features which are not present in the timeline view (not present in the roadmap or are in the parking lot), a list of total co-dependent features can be seen by clicking on the View button