:Trap Statement

 
       │
       :Trap <ecode>
       │
       code
       │
       │←────────────────────────────────────┐
       │                                     │
       ├───────┬───────┐                     │
       │       │       │                     │
       │       :Else   :Case[List] <ecode>   │
       │       │       │                     │
       │       │       │                     │
       │       │       │                     │
       │       code    code                  │
       │       │       │                     │
       │←──────┘       └─────────────────────┘
       │
       :End[Trap]
       │

Where ecode is a scalar or vector of ⎕TRAP event codes.

Within the :Trap control structure, :Case is used for a single event code and :CaseList for a vector of event codes.