The Reformed churches are a group of Protestant denominations historically related by a similar Calvinist system of doctrine but organizationally independent. Each nation in which the Reformed movement was originally established had its own church government. Several of these local churches have expanded to worldwide denominations and most have experienced splits into multiple denominations. Commitment to teaching the original Calvinism usually continues to be reflected in their official definitions of doctrine, but in some cases is no longer necessarily typical of these churches. A 1999 survey found 746 Reformed denominations worldwide.