Compatibility of SAS Data Library

This paper presents an overview of backwards and forwards compatibility between Versions 6 and 7 of the SAS System and is intended to be used as a reference in determining what manner of access is allowed. Furthermore, this paper takes into account differences in compatibility between the Base SAS System and when products such as SAS/CONNECT and SAS/SHARE are used. SAS I/O Services The I/O Services provided by the SAS System are essentially the same in Version 7 as they were in Version 6. The fundamental component of I/O Services is the ability to access a SAS Data Library and its members. A SAS Data Library can be visualized as follows: SAS Data Libraries The two major goals of Version 6 to Version 7 compatibility are to allow the most transparent access possible to Version 6 data and to prevent Version 7 data from being written to Version 6 data libraries, as that would render them corrupt and unusable by Version 6. Accessing Version 6 Libraries Version 6 libraries can be accessed in Version 7 as follows: libname v6lib ’path-to-v6-library’; where ’path-to-v6-library’ contains only Version 6 members. By using the same syntax used in Version 6, Version 7 of the SAS System is able to run existing SAS programs with no change. The engine used will be determined by the nature of the library; if the library is Version 6 (i.e., no Version 7 files are present) the Version 6 engine will be used. Due to the fact that the SAS System has to determine the engine, directly specifying the desired engine can save time in the libname assignment, as seen below: libname v6lib v6 ’path-to-v6-library’; Versions 6 and 7 Data Files in the Same Library On directory based hosts, Version 6 and Version 7 files have a different extension for data files, catalogs, views, etc. As a result, the SAS System is able to differentiate between the two. For example, consider the SAS System running under a UNIX operating system: