Universal 1562: Rel N ⇒ ¬ relative pronouns; N Rel & strict verb-initial ⇒ ¬ relative pronouns
Original
There are no relative pronouns (i.e., no strong pronouns moved to initial or final position) in prenominal relative clauses, nor in postnominal relative clauses in strict verb-initial languages.
Standardized
IF word order is strictly verb-initial, THEN there are no relative pronouns (i.e., no strong pronouns moved to initial or final position) in prenominal nor in postnominal relative clauses.
This correlation was also stated by Keenan. See the first part in #823; the second part in ##1554-1556.