ERL and ERR Function Details
 
Syntax
  ERR
  ERL
 
After an error, the function ERR returns the code for the error, and
the ERL function returns the line number where the error occurred.
Because ERR and ERL return meaningful values only after an error, they
are usually used in error-handling routines to determine the error and
the corrective action.
 
Because ERL and ERR are functions, you cannot use them on the left-hand
side of an assignment statement. However, you may indirectly set them with
the ERROR statement.
 
Differences from BASICA
 
The ERL function returns only the line number, not line label, located
before the line producing the error. If your program has no line
numbers, ERL always returns 0.