"Gross value added is the value of output less the value of intermediate consumption; it is a measure of the contribution to GDP made by an individual producer, industry or sector; gross value added is the source from which the primary incomes of the SNA are generated and is therefore carried forward into the primary distribution of income account." OECD, Paris
"Net value added is the value of output less the values of both intermediate consumption and consumption of fixed capital." OECD, Paris
"Value added at basic prices is calculated from the production value plus subsidies on products less the purchases of goods and services (other than those purchased for resale in the same condition) plus or minus the change in stocks of raw materials and consumables less other taxes on products which are linked to turnover but not deductible. It represents the value added by the various factor inputs in the operating activities of the unit concerned.
Income and expenditure classified as financial or extra-ordinary in company accounts is excluded from value added.
Value added at basic prices is calculated "gross" because value adjustments (such as depreciation) are not subtracted." OECD, Paris
Or visit e.g. Eurostat's "Detailed National Accounts SNA 2008 or SNA 1993 Value added and its components by activity ISIC Rev 3" database for a more granular view.
1) NACE: Statistical classification of economic activities in the European Community