The Australian Financial Markets Association has implemented changes to its bank bill swap rate convention, with effect this week.The publication time has been moved from 10.06 am Australian Eastern Standard Time to 10.15 am to allow more time for review before publication.BBSW represents the midpoint of the national best bid and offer in the locally traded market for AFMA prime bank legible securities.In circumstances where the best bid and offer fails to calculate under its normal methodology, AFMA has a fallback methodology.That fallback methodology has been amended with changes to the bid offer spread threshold and an override role for AFMA, as benchmark administrator, in dislocated market conditions.AFMA said prime banks continue to be obliged to make markets in normal market conditions at spreads of three basis points in the one, three and six month terms, and four bps in the two, four and five month terms.