SAS libraries can contain files that you create, or they can be one of several special
libraries that SAS provides for convenience, support, and customizing capability such as
the Work library. SAS does not limit the number of SAS files that you can store in a SAS
library.
Library Engines
Each SAS library is associated with a library engine. SAS library engines are software
components that form the interface between SAS and the SAS library. It is the SAS
library engine that locates files in a SAS library and renders the file contents to SAS in a
form that it can recognize. Library engines perform such tasks as:
reading and writing data
listing the files in the library
deleting and renaming files
SAS has a Multi Engine Architecture in order to read to and write from files in different
formats. Each SAS engine has specific processing characteristics, such as the ability to
process a SAS file generated by an older version of SAS
read database files created by other software programs
store and access files on disk or tape
determine how variables and observations are placed in a file
place data into memory from its physical location
transport SAS files between operating environments
You generally are not aware of the particular type of engine that is processing data at any
given time. If you issue an instruction that is not supported by the engine, an error
message is displayed in the SAS log. When needed, you can select a specific engine to
perform a task. But usually, you do not have to specify an engine, because SAS
automatically selects the appropriate one.
More than one engine might be involved in processing a DATA step; for example, one
engine might be used to input data, and another engine might be used to write
observations to the output data set.
For more information about library engines, including a list of engines available in Base
SAS, see “About Library Engines” on page 750.
Library Names
Physical Names and Logical Names (Librefs)
Before you can use a SAS library, you must tell SAS where it is. SAS recognizes SAS
libraries based on either operating environment naming conventions or SAS naming
conventions. There are two ways to define SAS libraries:
a physical location name that the operating environment recognizes
a logical name (libref) that you assign using the LIBNAME statement, LIBNAME
function, or the New Library window
Library Names 587

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