SAS
catalogs are special SAS files that store many different types of
information in smaller units called catalog entries. Each entry has
an entry type that identifies its purpose to SAS. A single SAS catalog
can contain several types of catalog entries. Some catalog entries
contain system information such as key definitions. Other catalog
entries contain application information such as window definitions,
help windows, formats, informats, macros, or graphics output. You
can list the contents of a catalog using various SAS features, such
as SAS Explorer and PROC CATALOG.