National accounts are compiled in accordance with the European System of Accounts - ESA 1995 (Regulation 2223/96 of the European Council, available on EUR-Lex).
Definitions, methods and accountings conventions can be found in the ESA95 which includes legal amendments and presents a consolidated version for the convenience of readers. Specifics aspects related to quarterly national accounts and explanations on methodology can be found in Eurostat's "Handbook on quarterly national account".
Specifics aspects of public finance data are treated in: http://europa.eu.int/estatref/info/sdds/en/gov/gov_index.htm
More information about concepts, definitions and classifications, data coverage, the dissemination policy and the compilation practices for European aggregates and seasonal adjustment can be found in the Euroindicators metadata files or in the quarterly and annual national account metadata files available on Eurostat site.
