:Trap Statement

 
       |
       :Trap <ecode>
       |
       code
       |
       |<------------------------------------.
       |                                     |
       .-------.-------.                     |
       |       |       |                     |
       |       :Else   :Case[List] <ecode>   |
       |       |       |                     |
       |       |       |                     |
       |       |       |                     |
       |       code    code                  |
       |       |       |                     |
       |<------'       `---------------------'
       |
       :End[Trap]
       |

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

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