Subject to the value of the USER= option, one-level data set names refer to the USER libname if such a libref is allocated; if not, they're written to WORK.
Here's an illustrative log. You can see how the same DATA statement is used in the two separate DATA steps (apparently implying the same output data set). Yet the NOTEs in the log show you how the behaviour changes after the USER libref has been assigned.
17 data demo;
18 x='first';
19 run;
NOTE: The data set WORK.DEMO has 1 observations and 1 variables.
20
21 libname user '~';
NOTE: Libref USER was successfully assigned as follows:
Engine: V9
Physical Name: /home/ratclac
22
23 data demo;
24 x='second';
25 run;
NOTE: The data set USER.DEMO has 1 observations and 1 variables.
Once the USER libref has been assigned, the only means of accessing the WORK library are:
- Clear the USER library, e.g. libname user clear;
- Specify WORK as the first qualifier for a data set name, e.g. data work.demo;
Knowledge of the USER option can form a very useful debugging technique whereby you can quickly switch your code between creating temporary work data sets (normal mode of operation) and permanent user data sets (for debugging).
You can find documentation at the links below:
http://support.sas.com/documentation/cdl/en/lrcon/62955/HTML/default/viewer.htm#a000930616.htm
http://support.sas.com/documentation/cdl/en/hostunx/61879/HTML/default/viewer.htm#userlib.htm
However, why can I find it in the Unix Companion but not the Windows Companion? In fact, why can't I find it in the OS-independent companion. Answers on a post card please. Am I simply being myopic??