The objective of this standard is the identification of requirements for rating systems to cloud computing services in order to provide enough warranty to users as to trust in the labels assigned to those services and the information they provide in their decision processes to procure cloud services. For this reason, these rating systems are mainly focused in characteristics related with the cloud service outcome (more than technologies used or management system implemented by cloud providers). The labelling of cloud services according to this standard becomes a powerful methods to provide transparency in the cloud services market, making easier the decision taking processes and contributing to a better way or work of this cloud market, because labels reduce the risk of adverse selection that are present nowadays in asymmetric cloud markets.