The Free On-line Dictionary of Computing (30 December 2018):

call-by-value-result

   An argument passing convention where the actual argument is
   a variable V whose value is copied to a local variable L
   inside the called function or procedure.  If the procedure
   modifies L, these changes will not affect V, which may also be
   in scope inside the procedure, until the procedure returns
   when the final value of L is copied to V.  Under
   call-by-reference changes to L would affect V immediately.
   Used, for example, by BBC BASIC V on the Acorn
   Archimedes.