I use 1.2345 since dashes are not allowed.
(I use a non-sequential fraction to indicat things that fall inbtween, like a short story, or a variation of the original
It is 1. because it contains the first book and will sort properly with other, non-omnibus titles within the series. (A now, common problem with Baen re-releases
of their backlist or old classics the have obtained rights to))
I also add a tag 'Omnibus edition'
