       10 // REF test program
       20 //
       30 DIM reeks(3)
       40 reeks:=8
       50 a$:="a$"
       60 aap(reeks, a$)
       70 FOR f:=1 TO 3 DO SYS assert, reeks(f)=1
       80 SYS assert, a$="b$"
       90 PRINT "Ok"
      100 //
      110 PROC aap(REF a(), REF b$)
      120   SYS assert, a(1)=8 AND a(2)=8 AND a(3)=8
      130   a:=1
      140   b$:="b$"
      150 ENDPROC aap
