In SAS OLAP the N-WAY summarization is created by default, however you have the option to not create the N-WAY & as I highlighted in a prior post, not creating it changes your OLAP type to either a HOLAP or ROLAP. But the real question is what the heck is this N-WAY thingy anyhow? For new SAS programmers this is probably a new term, but for SAS PROC SUMMARY and MEANS users this is ol' news. (In the SAS OLAP Documentation, it is actually stated that these two procedures were where the N-WAY term came from.)

The N-WAY option simply provides the lowest level summary of data. So by default, OLAP creates an N-WAY to house the lowest level of measures at ALL dimensional/hierarchy crossjoins.

If you have 3 dimensions - geography, product, business unit
with several levels within  - state/city, color/size/name, organization/department
and measures of              -  sales sum, returns sum, inventory sum

The N-WAY is the total sum of sales, returns and inventory at the cross join of all levels:
state-city-color-size-name-organization-department.
Such as:

...

In a report, if you'd like to see the total sales by city and organization, SAS takes the nway and on-the-fly sums up the 'lower' level data at the departments (as well summing up the product dimension) to give you the totals.
Such as: