Backwards compatibility of the RPM format

[Avi Kivity]

Hi, I'm considering moving from mock to rpmbuild, since simplifications 
in my build process now allow it and rpmbuild is generally faster.


A possible problem is incompatible changes in the format. If I build on 
Fedora 28+, will the resulting RPM be installable on RHEL? The RPM is 
self-contained and has no dependencies.


  - are the file formats compatible, and will they continue to be 
compatible? I know that compression algorithms have changed, but perhaps 
they were backported (or happened early enough to be included in RHEL)

  - are there flags I can specify to tell rpmbuild to restrict itself to 
an older feature set?

  - is this a supported practice, or do you recommend against for 
future-proofing?