Urban communities existing on the date of publication of the loi n° 99-586 du 12 juillet 1999 relative au renforcement et à la simplification de la coopération intercommunale ayant élargi ou non leurs compétences dans les conditions prévues au III de l’article L. 5215-20-1 are substituted, for the exercise of their competences alone, for the communes which are part of it when these are grouped with communes outside the community. This provision does not entail any change to the remit or scope of the communes unions concerned, which become mixed unions within the meaning of article L. 5711-1.