How to implement referential facilities in PostgreSQL

Hi everybody,

Happy New Year to you all.

We have a rather large M$ Access application for time and attendance
and job time registration. It has been implemented in M$ Access using a
M$ Access database running on a M$ 'operating system'.

One of our issues is to use the PostgreSQL in stead of/underneath the
M$ Access database application, which is the existing application running
well on M$ Access with not so large amounts of data. We of course need
to run this on a Linux box. The application makes extensive use of some
Access 'referential features'.

So my question is:

What is the equivalent of

'Enforce Referential Integrity',
'Cascade Update Related Fields', and
'Cascade Update Related Records' in

SQL/PostgreSQL terms. In other words, how do I get these facilities into
my PostgreSQL database? I need to be able to have the M$ Access application
to link directly to the PostgreSQL tables using ODBC, which I have managed
to copy directly using Access, but with no Primary/Foreign keys what so ever.

Thanks for any sugestions,

Leif