What is the purpose of the “version” parameter that is passed to most of the IDFS data access routines?
The purpose of the version parameter is to allow multiple file openings of the same IDFS data set within a single program or session. Once an IDFS data set has been opened, a set of file descriptors is assigned to the data set in question. The normal mode of operation for IDFS data processing is to process the data one record at a time, in time sequential order. If there is a need to search the same IDFS data set in multiple accesses, the use of the version parameter must come into play. For each unique combination of data key, extension and version parameters, a set of file descriptors is assigned and all file manipulations performed by the IDFS data access software will be independent of other file descriptors that may be accessing the same data set. As a general rule, the retrieval of multiple data parameters from a single IDFS data source does not constitute the need for multiple version numbers; a single version number will suffice. In addition, the simultaneous retrieval of data
