JOIN syntax

Looking at SQL92, it seems that I ought to be able to do this:

SELECT * FROM invoice INNER JOIN (SELECT * FROM invoice_line WHERE lineno > 1) 
ON invoice.invno = invoice_line.invno;
ERROR:  parser: parse error at or near "("

(I know it can be successfully expressed in a more complex WHERE clause).

Is there anything wrong with the syntax, or is it a missing feature?

-- 
Oliver Elphick                                Oliver.Elphick@lfix.co.uk
Isle of Wight                              http://www.lfix.co.uk/oliver
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