```
    C4Context
      title System Context diagram for Internet Banking System

      Person(customerA, "Banking Customer A", "A customer of the bank, with personal bank accounts.")
      Person(customerB, "Banking Customer B")
      Person_Ext(customerC, "Banking Customer C")
      System(SystemAA, "Internet Banking System", "Allows customers to view information about their bank accounts, and make payments.")

      Person(customerD, "Banking Customer D", "A customer of the bank, <br/> with personal bank accounts.")

      Enterprise_Boundary(b1, "BankBoundary") {

        SystemDb_Ext(SystemE, "Mainframe Banking System", "Stores all of the core banking information about customers, accounts, transactions, etc.")

        System_Boundary(b2, "BankBoundary2") {
          System(SystemA, "Banking System A")
          System(SystemB, "Banking System B", "A system of the bank, with personal bank accounts.")
        }

        System_Ext(SystemC, "E-mail system", "The internal Microsoft Exchange e-mail system.")
        SystemDb(SystemD, "Banking System D Database", "A system of the bank, with personal bank accounts.")

        Boundary(b3, "BankBoundary3", "boundary") {
          SystemQueue(SystemF, "Banking System F Queue", "A system of the bank, with personal bank accounts.")
          SystemQueue_Ext(SystemG, "Banking System G Queue", "A system of the bank, with personal bank accounts.")
        }
      }

      BiRel(customerA, SystemAA, "Uses")
      BiRel(SystemAA, SystemE, "Uses")
      Rel(SystemAA, SystemC, "Sends e-mails", "SMTP")
      Rel(SystemC, customerA, "Sends e-mails to")
```

```
    C4Context
      title System Context diagram for Internet Banking System

      Person(customerA, "Banking Customer A", "A customer of the bank, with personal bank accounts.")
      Person(customerB, "Banking Customer B")
      Person_Ext(customerC, "Banking Customer C")
      System(SystemAA, "Internet Banking System", "Allows customers to view information about their bank accounts, and make payments.")

      Person(customerD, "Banking Customer D", "A customer of the bank, <br/> with personal bank accounts.")

      Enterprise_Boundary(b1, "BankBoundary") {

        SystemDb_Ext(SystemE, "Mainframe Banking System", "Stores all of the core banking information about customers, accounts, transactions, etc.")

        System_Boundary(b2, "BankBoundary2") {
          System(SystemA, "Banking System A")
          System(SystemB, "Banking System B", "A system of the bank, with personal bank accounts.")
        }

        System_Ext(SystemC, "E-mail system", "The internal Microsoft Exchange e-mail system.")
        SystemDb(SystemD, "Banking System D Database", "A system of the bank, with personal bank accounts.")

        Boundary(b3, "BankBoundary3", "boundary") {
          SystemQueue(SystemF, "Banking System F Queue", "A system of the bank, with personal bank accounts.")
          SystemQueue_Ext(SystemG, "Banking System G Queue", "A system of the bank, with personal bank accounts.")
        }
      }

      BiRel(customerA, SystemAA, "Uses")
      BiRel(SystemAA, SystemE, "Uses")
      Rel(SystemAA, SystemC, "Sends e-mails", "SMTP")
      Rel(SystemC, customerA, "Sends e-mails to")
```

For an example, see the source code demos/index.html

 - System Context
 - Container diagram
 - Component diagram
 - Dynamic diagram
 - Deployment diagram