Documentation on Preseed Partman options?

[shinobi]

Documentation on Preseed Partman options? There does not seem to be a complete reference anywhere? No authoritative use guide? I find 100s if not 1000s of examples, but nothing exhaustive. For example, I can't seem to find any explanation of the following options?

d-i partman-auto-lvm/guided_size string
d-i partman-md/confirm boolean
d-i partman-md/confirm_nooverwrite boolean
d-i partman/unmount_active boolean
d-i partman-auto/purge_lvm_from_device boolean

The official Debian documentation for Preseed files, it very limited in the scope of Partman, and is nothing more than another quite limited example of how to use Partman, but somewhere this has to be an exhaustive reference? No?