On April 10th 2018 a group directly involved in current Personal Health Train projects got together at the GO FAIR International Support and Coordination Office, in Leiden, to discuss the definition of the main architectural elements of the system, alignments among the different projects and forms of closer collaborations. Besides the more concrete definition of some of these elements, the group agreed on starting three working groups, namely, (i) Architecture, to progress the definition of the main architectural elements, (ii) Use Cases, to identify and define use cases aiming at serving the bases for the assessment of requirements of the architecture as well as for later validation of the same architectural elements, and (iii) Legal, to define the legal boundaries of the proposed Personal Health Train ecosystem.