Apparently there used to be a mechanism where an alias element in a top-level LDML element could serve to provide a parent locale as its source attribute. That is long gone and, since at least a decade ago, alias elements only ever appear in root.xml, with source="locale" and a path that starts ../ (so is a relative XPath). Ditch some complications (that I transcribed faithfully five-ish years ago when transforming the scripts), replacing them with assertions that check what's now documented in the LDML spec and confirmed by my own grep-checks in the CLDR data. This incidentally made one prior (weaker) check redundant, so I've now removed that from the look-up for the tags that identify a locale. That look-up is only ever performed after the DOM root nodes it uses have come through the scan of locale roots that now does the stronger check. Makes no difference to generated data. Change-Id: I811ffbef5f5ecb69183d68fa8bda57281f2a579d Reviewed-by: Mate Barany <mate.barany@qt.io>