User defined types -- Social Security number...

Anyone have a good pre-built user-defined type definition for creating /
maintaining / manipulating a SSN ... where valid chars are in the range
000-00-0000 through 999-99-9999.

I imagine that the storage column is probably varchar(11) -- I am looking
for a type definition that
   1) checks that all numbers are in the range [0..9]   2) inserts the dashes at position   3) accepts either
'000123456'OR '000-12-3456' as the input   4) leading zeroes (as in the above) must be stored -- hence varchar(11)
 
instead of numeric   5) always outputs in thje format '000-12-3456'

Either that or the question is: How can I coerce postgreSQL into using an
input / output "mask"...

-- 
Greg Patnude / The Digital Demention
2916 East Upper Hayden Lake Road
Hayden Lake, ID 83835
(208) 762-0762