Librefs remain in effect until the LIBNAME statement is changed, canceled, or until the SAS session ends.

When you are using the default engine, you do not have to specify the engine name in the LIBNAME statement. However, you do have to specify the libref and the SAS data library name.

A SAS engine is a set of internal instructions that SAS uses for writing to and reading from files in a SAS library. Each engine specifies the file format for files that are stored in the library, which in turn enables SAS to access files with a particular format. Some engines access SAS files, and other engines support access to other vendors' files.

To print a summary of library contents with the CONTENTS procedure, use a period to append the _ALL_ option to the libref. Adding the NODS option suppresses detailed information about the files.

Librefs must be 1 to 8 characters long, must begin with a letter or underscore, and can contain only numbers, letters, or underscores. After you assign a libref, you specify it as the first level in the two-level name for a SAS file.

The CONTENTS procedure creates a report that contains the contents of a library or the descriptor information for an individual SAS data set.

The LIBNAME statement is global, which means that librefs stay in effect until changed or canceled, or until the SAS session ends. Therefore, the LIBNAME statement assigns the libref for the current SAS session only. You must assign a libref before accessing SAS files that are stored in a permanent SAS data library.

The LIBNAME statement does not specify an engine. Therefore, it uses a default engine to create the States library.