How to combine multiple field primary key and Row Versioning

Hello,

I use Postgrsql 7.0.2 and ODBC 7.1.003. I discovered, that Row Versioning doesn't work with multiple field primary keys.
I need Row Versioning to be able to change tuples of a table, inserted by a function and I use multiple field primary keys to be sure, that inserted data are correct ie table *sortiment* contains the articles of each year
create table sortiment(
year integer,
article_nr integer,
number integer,
primary key(year,article_nr)
);

Are there further releases, which can combine multiple field primary keys and Row Versioning, or does anyone have any ideas, how to solve this confict?

Thanks in advance for any hint
Irina

E-Mail: i(dot)hasenoehrl(at)aon(dot)at