[Jprogramming] Rank error from what?

[Miller, Raul D]

I get this same behavior on j5.04 and j6beta:

   NB. words designed to help me understand a point left ambiguous
   NB. in the documentation on 18!:4
   foo=: 3 : 0
showlocale ''
showlocale_base_ @: (18!:4) y.
showlocale_base ''
)
   bar=: 3 : 0
showlocale ''
showlocale_base_ @: foo ''
showlocale_base_ ''
)
   showlocale=: ((0 0$0)"_)@ echo @ (18!:5) @ (''"_)
   echo =: 1!:2&2

   NB. create a locale
   18!:3<'bagle'

   NB. try to watch what 18!:4 means
   bar <'bagle'
+----+
|base|
+----+
+----+
|base|
+----+
|rank error: foo
|       showlocale_base_@(18!:4)y.


My question is: what is the rank error?

-- 
Raul