You don't want all available catalogs to be displayed during the catalog update, but only certain ones?

The procedure is described at Section 1.3.3.1.2.2.1, “Menu item "Online update" ” > Manage include/exclude lists.... [Manage include/exclude lists...]

The Entries for catalogs to be displayed and not to be displayed are made in the Configuration file partupdate.cfg > block [catalog] in the keys include_catalogs and exclude_catalogs.