A1. (meta)data are retrievable by their identifier using a standardized communications protocol.

A1.1 the protocol is open, free, and universally implementable.

A1.2 the protocol allows for an authentication and authorization procedure, where necessary.

A2. metadata are accessible, even when the data are no longer available.

Data and their metadata should be retrievable using their (persistent) identifier. Your data should be freely available, ideally via a repository. If access to data needs to be restricted, make sure that your selected repository offers authentication and authorisation.

Not all data can be freely shared; restricting access to data may, under certain conditions, be in accordance with the FAIR principles (for example, if the data contain personal or sensitive information, or are related to national security, etc.). If access to data is restricted, then at least metadata should be freely accessible, including information that the given dataset exists and general information about its contents. Metadata should also include information regarding access conditions and limitations, for example, they should specify the conditions under which accessing the data is possible.