Reading sequence diagram from http://www.ibm.com/developerworks/rational/library/3101.html
1. Frame
2. Lifeline
3. Messages
- Synchronus / Asynchronus
- Returns / Not
- Self message / Not
4. Guards
5. Combined Fragments
- Alternatives
- Options
- Loop
- Break
- Parallel
6. Referencing Sequence Diagrams
7. Gates