The workflow allows to define changes the various project members are allowed to make on the Issues, according to their type.

Select the role and the tracker for which you want to modify the workflow, then click Edit. The screen allows you then to modify the authorized change, for the chosen role and tracker. The Current Status options indicate the initial request status. The "New Statuses allowed" columns stand for the authorized status to apply.

Note: In order for a particular Role to change an Issue status, the authorization must be given to it explicitly, regardless of the workflow configuration.

In the above example, Bug type Issue requests with a New status could be given an Assigned or Resolved status by the Developer role. Those with an Assigned status could get a Resolved status. The status of all the other Bug type requests cannot be modified by the Developer.