What release of Enterprise Architect are you using?
The web Help page you linked to is rather old. I believe that the web Help has been updated since that page was loaded, and we might be in the process of updating it again. However, it is usually better to refer to the Help loaded with your installation of Enterprise Architect. For release 10, build 1007 of EA, the Archimate page describes a more extensive set of Toolbox pages, and includes the following paragraphs:
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You can modify the appearance of elements by toggling the
Advanced | Use Rectangle Notation context menu option on the element in a diagram.
For Artifact, Process, Function, Interaction, Service, Event, Actor, Role, Collaboration, Interface, Component, Node and Device elements:
- Select Use Rectangle Notation to show a rectangle with a decoration in the top corner
- Deselect Use Rectangle Notation to show the iconic representation of the element
You can set an Interface element to
provided,
required,
symmetric or
assembly, through its
interfacekind Tagged Value. If
Use Rectangle Notation is unselected, the orientation of the interface shape is determined automatically by the edge to which an incoming connector is attached.
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Edit: And ... KP got there first!