i386/x86_64 rpms on x86_64

[Jack Howarth]

    Is there a good resource to read which will explain how rpm handles
x86_64 and i386 packages on Fedora Core 4 x86_64? For example, by default
only the ncurses and ncurses-devel packages built for x86_64 are installed.
It is unclear how one should install the missing i386 built packages. I
have used 'rpm -ivh' since I was concerned that 'rpm -Uvh' might remove
the x86_64 built libraries and break things. Now when I do...

rpm -qa | grep ncurses

...I see...

ncurses-devel-5.4-17
ncurses-5.4-17
ncurses-devel-5.4-17
ncurses-5.4-17

However when I do 'rpm -ql ncurses-5.4-17' I only seem to see the
files for the x86_64 built binaries. It would nice if there was
a set of clear rules for working with rpm in a mixed architecture
environment. Thanks in advance for any clarifications.
         Jack