The descriptor portion is information
that SAS creates and maintains about each SAS data set, including
data set attributes and variable attributes. Here are examples:
-
the name of the data set and its
member type
-
the date and time that the data
set was created
-
the names, data types (character
or numeric), and lengths of the variables
Extended attribute descriptor
information is defined by the user and includes the name of the attribute,
the name of the variable, and the value of the attribute. The descriptor
information also contains information about extended attributes (if
defined in a data set). You can use the CONTENTS procedure to display
descriptor information.
proc contents data=work.update;
run;
At this point, the data
set contains the six variables that are defined in the input data
set and in the assignment statement. _N_ and _ERROR_ are not written
to the data set. There are no observations because the DATA step has
not yet executed. During execution, each raw data record is processed
and is then written to the data set as an observation.