(19)It should be clarified that, for the estimation of the value of a contract, all revenues have to be taken into account, whether received from the contracting authority or from third parties. It should also be clarified that, for the purpose of estimating the thresholds, the notion of similar supplies should be understood as products which are intended for identical or similar uses, such as supplies of a range of foods or of various items of office furniture. Typically, an economic operator active in the field concerned would be likely to carry such supplies as part of his normal product range.