Data carts, their persistent identifiers, and how they can be used
To create a referenceable cart, simply put all data you used in it using the ESGF search interface. When you have completed your cart, you can request a PID to be assigned to it; note that, once a PID has been assigned, the constituency of the cart is fixed and can never be changed. The identifier will continue to be a stable reference back to your individual data collection and you can include it in your article text. For example, you could mention the cart’s persistent identifier in a note in the introductory section or at the end of your article.
Data carts enable precise statements about data you used, improving transparency of your work and making it easier for others to directly build upon your efforts. Be aware, however, that a reference to a data cart is not considered an adequate replacement for giving proper credit through formal citation of data products. You should always formally cite the whole data from which you took parts into your cart by citing the respective DataCite DOIs, thereby also giving academic credit to those involved in producing the data
The data you put in your cart will keep to be listed in it, even if data objects are unpublished or replaced by new versions. In such cases, some minimal information on the obsolete data objects will remain visible in the web interface, with possible linking to the most recent version of a data object. There is, however, no guarantee that the data you put in your cart are available over longer time spans, unless those data belong to final data products that have undergone archiving. A safe indication for this is that there is a DataCite DOI available for an aggregated product of which the data you used is part of.
Data carts work by aggregating a list of data product PIDs, which are automatically generated by ESGF for CMIP6 data. You can also put non-CMIP6 data in your cart – it will then be internally referenced through its DRS syntax and there may be less metadata available for these products in case they are removed or succeeded by new versions. The cart and its PID will however continue to work, independent of which project the referenced data belong to.