Directives
ON ... GOSUB /GOTO/EVENT  
  The ON directive has four formats, two which provide condition execution based on the value of a numeric expression, one is used to define how to process EVENTS from OCX controls, and a fourth to define structured Error handling. Please select the format you are interested in
   
Formats ON numexpr GOSUB stmtref,... Jump to a subroutine value based on the value of a numeric expression
  ON numexpr GOTO stmtref,... Transfer control to a stament value based on the value of a numeric expression
  ON EVENT ...... Control the processing of events as received from external controls
  ... ON ERR directive(s)... Define Error logic for GOSUB, WHILE, FOR, REPEAT and SELECT directives.

Structured error handling is +PxPlus Exclusive