[gentoo-user] emerge --changed-use @world : how to interpret its output?

[Helmut Jarausch]

Hi,
I have difficulties to interpret the output of

nice -19 emerge -av1 --update --keep-going --tree --changed-use \
     --unordered-display --verbose-conflicts @world
I get LOTS of request to change package.use to include abi_x86_32.

It looks like emerge wants to change half of system (which is nearly  
abi_x86_64 only)
to use the 32 bit ABI, as well.

How can I find out which packages triggers this chain of re-emerges?

Many thanks for a hint,
Helmut