why format procedure produce error?

[Changying Li <lchangying@gmail.com>]

in the guile manual:
 -- Scheme Procedure: format dest fmt [args...]
     Write output specified by the FMT string to DEST.  DEST can be an
     output port, `#t' for `current-output-port' (*note Default
     Ports::), a number for `current-error-port', or `#f' to return the
     output as a string.

what's the meaning of NUMBER?
I want to write things to error port, so I write
(format 1 "hello")

standard input:5:1: In procedure simple-format in expression (format 1 "hello"):
standard input:5:1: Wrong type argument in position 1: 1
ABORT: (wrong-type-arg)


it work when I use (format (current-error-port) "hello")

Is there something wrong in the guile manual ?


-- 

Thanks & Regards

Changying Li