The DATASET_... functions (documented in Deprecated Functions [1]) were deprecated as of verson 2.5. New SUBSET functions, in combination with other existing functions, are more flexible and efficient.
See also: Functions Guide [2] Guide to SUBSET functions [3] Deprecated Functions [1]
Links:
[1] http://kb.visokio.com/kb/functions-guide-deprecated
[2] http://kb.visokio.com/functions-guide
[3] http://kb.visokio.com/kb/subset-functions