I have a 64 bit rpm package that "requires" a 32bit version of libstdc++. I know that the "requires:" line is like : requires: libstdc++ >= <some version/ rel> but I do not know how to specify the 32 bit version.

To make it a little more complicated, I need the package to work on OpenSuse and on RHEL. I figured out that :
On Suse : rpm -qa --qf '%{NAME}-%{VERSION}(%{ARCH})\n' | grep ^libstdc | grep 32bit | grep -v devel
On RHEL : rpm -qa --qf '%{NAME}-%{VERSION}(%{ARCH})\n' | grep ^libstdc | grep i[3456]86 | grep -v devel

Would tell if it is installed. I could put these checks in the %prep section . I wonder if the is a way to do this using the "requires: " tag.