I've been using MDX generated by MS Reporting Services as a starting
point for my own queries. It typically builds nested FROM clauses like
this one:

FROM ( SELECT {[Product].[Class].&[ABC]} ON COLUMNS
FROM ( SELECT {[Product].[Dept].&[18]} ON COLUMNS
FROM [MyCube]))

Now, it seems this query could be created using a WHERE clause just as
easily.

I'm wondering what the reasons would be for putting things in a FROM
clause rather than the WHERE clause.

TIA,
Jim