Several European countries, as well as the European Commission, have acknowledged the importance of open standards (under various definitions of that term) and have taken steps accordingly. Formal (e.g. ISO) standards are often referred to in software development and procurement, but may not necessarily also be open standards. The authors consider the application of formal standards where national policy promotes their use, and, since much contemporary software development involves open source software, they further consider the interaction between the requirement to comply with open standards, and the implementation of open and formal standards in open source software, with particular reference to patent licensing. It is shown that not all formal standards are open standards. SSO policies and procedures regarding the notification of standards-essential patents (SEPs) present challenges for organisations wishing to implement standards in software since such policies and procedures need to be compliant with procurement requirements, patent licences and open source software licences. This paper draws out some implications for those organisations (differentiating where appropriate between small companies and other organisations) and suggests a number of ways of addressing the challenges identified. Use of formal standards may create barriers for implementation in open source software and inhibit an open and inclusive business-friendly ecosystem, and to avoid such barriers is of particular importance for small companies that are essential players in an innovative and international society.