the data as of the date specified by the user the version control logic 20 searches for inserting ec 39 s having an effective date on or before the specified date and satisfying one of the following 1 the ec controlled object instance is unextracted 2 the effective date of the extracting ec is later than the specified date or 3 no effective date has been assigned to the extracting ec the 34 range of effective dates 34 option gives a composite view of the production level of data over a period of time specified by user input the search criteria that must be satisfied are that the effective date of the inserting ec is on or before the specified end date the 34 to 34 date and one of the following 1 the ec controlled object instance is unextracted or 2 the effective date of the extracting ec is later than the specified start date the 34 from 34 date or 3 no effective date has been assigned to the extracting ec finally the 34 effective between two ec 39 s 34 option provides a composite view of the design level of the data between the starting and ending ec 39 s specified by the user this option can serve a useful planning purpose such as reviewing the engineering changes which have been accepted to decide when they should be made effective the search criteria used are that the inserting ec is earlier than or equal to the ending ec the 34 to 34 ec specified by the user and either the ec controlled object instance is unextracted or the effective date of the extracting ec is later than the starting ec the 34 from 34 ec.