There is the possibility to display a direction (plain arrow for example) on connectors. This information is only graphical and not semantic. This capability can be driven by a dedicated CSS syntax or through properties view.
There are two possibities to set connection decoration on existing link, with properties view or with CSS. Available decorations are added through extension point, except for two which are:
To use it activate the Advance Tabulation: In Window > Preferences > Papyrus > Property views > Select Diagram Advanced Notation (plugin), Apply and close. Select the edge to customize, 'Advance Tabulation'' is now visible under Appearance. You can set source and target decoration.
Attributes sourceDecoration and targetDecoration permit to set source and target decoration on link. The list of available decoration values is accessible with the autocompletion (Ctrl+Space).
New decoration can be added through extension point:
org.eclipse.papyrus.infra.gmfdiag.common.connectionDecoration
Attributes:
Added decorations will be available in advance properties tab and in the CSS autocompletion.
The full compliance is guaranteed for Stereotype Property Reference Link and for Connector Link.