UDC Summary (udcS) for short - represents a selection of around 2,600 classes extracted from the UDC Master Reference File (UDC MRF) 2011 which contains over 70,000 classes. The selection comprises main numbers, common auxiliary numbers and special auxiliary numbers and it represents even coverage of all areas of knowledge as contained by the scheme.

The version published in Finto is a trilingual classification extracted from the main UDC Summary SKOS file and contains labels in Finnish, Swedish and English.