Create the Annotate data set, CITYSTAR.
CITYSTAR contains the commands that draw a star and a label at each of the
three cities. Because the RETAIN statement sets the value of FUNCTION to LABEL
and no other function is specified, every observation uses LABEL. Setting
WHEN to A draws the annotation after the map.
data citystar;
length function style color $ 8 position $ 1
text $ 20;
retain function 'label' xsys ysys '2' hsys '3'
when 'a';