1. Apparatus for configuring a control system, comprising: a first model representing a first configuration of at least one of the control system and a system controlled thereby, and a second model representing a second configuration of at least one of the same control system and the same system controlled thereby, wherein the second model is a copy of the first model that has been modified independently of the first model, wherein the second model is further modified on a computer separate from a computer on which the first model resides, comprising a record of modifications to the second model, wherein the record can be played against the first model in connection with merging the first and second models, a third model representing a third configuration of at least one of the same control system and the same system controlled thereby, the third model representing a merge of the first and second models.