userdefined types

Hello,
  So I have been reading over the web and it seems that one must
define two methods before declaring a type. But I seem to have done it
(CREATE  TYPE) without creating any functions and it did not give me
an error. I tried to use

INSERT TABLENAME SET user-defined-column = ROW('val1' ,'va2' ...);

and it works. The only problem is when I have ROW( , ,
'values','morevalues', ,'evenmorevalues');

it does not like the commas one after the other (empty value) .... how
do I solve that .... or does this have something to do with those two
methods (in and out) that I overlooked.

any insight would be much appreciated.

-assad