This is useful if the install.wim contains multiple Windows versions
(e.g., Home, Pro, ..), because the autounattend file will always select
index 1. With this mechanism, a variant different from the first one can
be automatically selected. imageSelection can be either an index (1-N)
or the image name wiminfo can list all images contained in a given WIM
file.
The default case is index 1, which has the same effect as before, with
the possibility of having a slightly smaller install.wim file because
all unwanted variants are discarded.
With newer Windows 10 versions, `install.wim` can become larger than
4GiB, which can't be placed in a FAT32 partition anymore. By splitting
it into chunks with `wimsplit` and removing `install.wim`, the larger
images work fine.
Markus Partheymüller