Can you tell me what this means? thanks

[deleted_user]

%IF %SYSFUNC ( EXIST(MYLIB.CONTROLS)) = 1
%THEN %DO;
PROC DATASETS LIBRARY=mylib NOLIST;
DELETE CONTROLS;
RUN;
%END;
I'm a newer, I only know %SYSFUNC function for automatic macro variables likes sysdate9; how THATcan be used with A data file ((MYLIB.CONTROLS),
AND what means for EXIST?
THANKS A MILLION IN ADVANCE.
SASJUNIOR

[ieva]

It is exist function, you can read more about that in http://support.sas.com/documentation/cdl/en/lrdict/63026/HTML/default/viewer.htm#a000210903.htm