how to define 'recent' for use in 'ls'?

[michael <linux@networkingnewsletter.org.uk>]

from the ls man page I see:
       --time-style=STYLE
              show times using style STYLE: full-iso, long-iso, iso,
locale, +FORMAT

              FORMAT is interpreted like `date'; if FORMAT is
FORMAT1<newline>FORMAT2,  FORMAT1
              applies  to  non-recent  files  and FORMAT2 to recent
files; if STYLE is prefixed
              with `posix-', STYLE takes effect only outside the POSIX
locale


and indeed ls gives different outputs depending on age of file, eg

-rw-r--r--  1 michael michael   6021 Mar  9 23:25
bldit.bcon.a1a_v4_3-qssa.030905.log
-rw-r--r--  1 michael michael  21692 Jan 16  2005
bldit.cctm.a1a_v4_3-smvgear.011605.log

but how do I define what is (non-)recent? I presume this is connect with
locale but man locale has no 'recent' string in it!

Thanks,
-- 
Michael Bane
Atmospheric Physics Group
University of Manchester