The International Patient Summary Standard (EN 17269) normalizes the dataset within the European Guideline on cross-border exchange of a patient summary. This dataset has been widely appreciated and been taken as the basis for projects in both Europe and wider afield, e.g. U.S.A, Canada and more. The dataset is a relatively mature dataset and it is currently in its third iteration (i.e., 2013, 2016, 2020). Even so, to move from a policy-driven guideline to a formal standard was not straight forward. The paper describes how the ‘minimal and non-exhaustive’ dataset could be the basis for a reference standard; one that was intended to facilitate both an ‘implementable’ and ‘sustainable’ solution. In particular, the requirement of ‘extensibility’ for the standard dataset had to be addressed.