TM1SubsetAll, Members, member range

The basis for many queries, this returns (almost, see below) the entire dimension, which is the equivalent of clicking the ‘All’ button in the Subset Editor.
TM1SUBSETALL( [Product] )

Note that only the final instance in the first hierarchy of members that are consolidated multiple times is returned.

The Members function, on the other hand, delivers the full dimension, duplicates included:
[Product].Members

A range of contiguous members from the same level can be selected by specifying the first and last member of the set you require with a colon between them.
This example returns Jan 1st through to Jan 12th 1972.
{[Date].[1972-01-01]:[Date].[1972-01-12]}