The answer I am going to give, is......maybe
Can you please be more specific on what you want to do with grouped data tables. Save them like a zip file, be able to pass them to users to colleagues?
You are also asking on how subset works. Basically one can select out of a data table, the rows an columns they want, and place them into a new separate data table. The table can either be independent of the table it was drawn from, or one can keep the tables linked, so if items change in either of the tables, it is reflected in the other. Subsetting can be easily done in an interactive mode, using
Tables=>Subset
or in a programmatic mode using JSL
names default to here( 1 );
dt = current data table();
dtNew = dt << subset( columns( a list of columns), rows(a list of rows, or one can specify to use rows that have been selected in the data table));
Jim