On technical grounds indices can be divided between those which combine results of various datasets at the macro-level, and those which use only one (micro)-data source. The distinction is important mainly to understand the technical particularities and the ability of the index to serve as a basis for further analysis. One of the most widely known examples of a 'macro' development index is the Human Development Index (HDI) as used in UNDP's annual Human Development Reports (e.g. 2010, 2013).