Lower-level constructions tend to be diachronically more stable than higher-level constructions. In a given synchronic state, they therefore tend to be older. This can be used in internal reconstruction of word order:

• If the order of determinans – determinatum in a nominal compound differs from the order of head – possessive attribute, then reconstruct the former order for the original possessive attribute.
• If the order of determinans – determinatum in a verbal compound differs from the order of verb – nominal dependent, then reconstruct the former order for the original verbal syntax.
• If main constituent order in subordinate clauses differs from main constituent order in main clauses, then reconstruct the former for original main clauses.