DOCBOOK: catalog question

Hi,

I have a question about the catalog I use.

I created it like this:

cat /usr/lib/sgml/dsssl.cat /usr/lib/sgml/docbook.cat > /usr/lib/sgml/catalog

/usr/lib/sgml/dsssl.cat comes from the jade-1.2.1-4.i386.rpm
and /usr/lib/sgml/docbook.cat from unzip -d /usr/lib/sgml docbk31.zip

Is this the correct procedure? It seems to work..
What do I do with the catalogs in db152.zip ?

Regards,

Maarten