"Data portability" is vague so that the law is stable and flexible. As a comparison, "drivers need to adapt driving speed to weather conditions" is equally vague. It would simply be infeasible to publish an hourly speed limit chart based on rain, fog, snow, etc. It is the responsibility of driving instructors to raise awareness on reasons to adapt the speed. Drivers need to then interpret that clause to their situation.

Similarly, it is up to industry -- either via standardization bodies or courts -- to clarify what exactly is "data portability".

the phrase maybe, but the gdpr article itself provides more "Article 20

Right to data portability

1. The data subject shall have the right to receive the personal data concerning him or her, which he or she has provided to a controller, in a structured, commonly used and machine-readable format and have the right to transmit those data to another controller without hindrance from the controller to which the personal data have been provided, where:" https://eur-lex.europa.eu/eli/reg/2016/679/oj#d1e2753-1-1

> It would simply be infeasible to publish an hourly speed limit chart based on rain, fog, snow, etc.

Not really. Pretty sure tire makers have good data on traction at different speed, temperature and substrate.

so the law would state that you need to constantly check your phone for the app that tells the current speed limit based on weather, road type, road size, car size, tire type, and traffic