Sequence Diagram Modelling

  Hello   Concerning the way to model the sequence diagrams or collaboration diagrams.   I would like to know what is the best model that can be used to do it?   Aris model - EPC  - enables to connect the following objects: Event and Function but not between Event and Application System Type - enables only one relatioship of the same type between two same objects   Aris model - Program Flow Chart - enables to connect the following objects: Event and Application System Type but not between Event and Function - enable several relationships of the same type "provides input for" or "transmits data to" between two same objects. The last one enables to associate one or several diagrams to the relationship   Aris model - UML Sequence Diagram (IT Architect Licence) - the number of objects is very poor (e.g. the following objects are not available: event, application system type...)

> hereafter examples of  collaboration diagram and sequence diagram