My first goal will be to strip 2 items that XAR does not have, the  
rpm lead and
signature header. The lead will be discarded, the signature tags will be
appended to the metadata header (which is what currently happens now
when a *.rpm package is read, see headerMergeLegacySigs in lib/ 
package.c)

At that point, XAR and RPM have a fundamentally equivalent archive  
format
consisting of contiguous metadata blob, plus a payload.

This is likely to break everything on HEAD. You've been warned. ;-)

73 de Jeff