current data set
Typically used when additional derivations have been produced by proc processdata or tabulate, in order to
return to the original data set, or to "pop back" to an earlier data set on the stack.
Note: proc getdata always clears the stack and its result becomes dataset 1.
If no attributes are specified, default is pop: all.
all | n
If all, pop back to the original data set (proc getdata).
Otherwise, pop back n data sets.
After this is done, data sets above the current one in the stack are removed and unavailable.
Set any data field names that will be in effect. Field names are not retained in the data set stack structure,
so if a data set that had field names is made the current data set, the field names must be respecified here
using this attribute.
Stack element n becomes the current data set for plotting.
Discontinued as of version 2.40.