SO
How can i model an external Organizational Unit ?i mean is there any object type that can be used to represent an external group or a unit; like the object external person object?
There is no symbol for an External Oraganizational Unit in the symbols provided with ARIS. There are several options for creating your own. You could create a custom symbol, you could set an attribute (and display it as text or a symbol with the object using a template if you ilke) or you could use a different background color for the object.