The initramfs (in the <code>boot.img</code> file!) will automatically find and mount the pmOS boot and root partition, load the <code>initramfs-extra</code> (which contains additional files, it was split to save space) and take care of booting through until [https://github.com/postmarketOS/pmbootstrap/wiki/Glossary#openrc OpenRC] takes over.
The <code>userdata</code> partition is not used yet (proposal to do that is in [https://github.com/postmarketOS/pmbootstrap/issues/60 #60]). But as we are pretty flexible, you can also flash pmOS to the <code>userdata</code> partition, if it has more space and you can't fit it on the <code>system</code> partition. The initramfs will detect it anyway. Just make sure, that you don't have it flashed to ''both'' partitions!
To flash to the <code>userdata</code> partition instead of the <code>system</code> partition, use <code>pmbootstrap flasher flash_rootfs --partition=USERDATA</code>.
=== Future ideas ===