Amendments to the rules for next year's election would have to follow Preparatory Committee guidelines, an official said yesterday. Principal Government Counsel James O'Neil told a provisional legislature bills committee the guidelines, announced in May, were legally binding. Provisional legislator Andrew Wong Wang-fat asked who would decide whether an amendment was in line with the guidelines. Deputy Secretary for Constitutional Affairs Ng Shek-hon said the provisional legislature president would decide, and Mr O'Neil said it could be dealt with under Legco standing orders. Some legislators want the 20 geographical seats chosen by the single-seat, single-vote model, contrary to the guidelines..