DATE(year, month, day, hour, minute, second, millisecond, timezone)
For creating date values using numerical values.
E.g. DATE(2007, 2, 1) for 1st Feb 2007.

ROWINDEXSUBSET(rowIndex, operator)
For specifying subsets by row index.
E.g. ROWINDEXSUBSET(5) for the 5th record only
E.g. ROWINDEXSUBSET(CURRENTROW, "<=") for all records up to and including the current record.
These can be combined using UNION and INTERSECTION as needed, before being supplied to one of the subset-accepting functions such as SUBSET_MEAN.

Both are scriptable.