Referencing Source Code Artifacts: a Separate Concern in Software Citation
This work tackles the problem of reliably citing software source code for researchers and developers, but it is incremental as it builds on existing identifier concepts.
The paper addresses the need for unique, persistent identifiers that intrinsically support integrity checking for referencing software source code to ensure scientific reproducibility, and details the syntax, semantics, and implementation of persistent identifiers used by the Software Heritage project for billions of artifacts.
Among the entities involved in software citation, software source code requires special attention, due to the role it plays in ensuring scientific reproducibility. To reference source code we need identifiers that are not only unique and persistent, but also support \emph{integrity} checking intrinsically. Suitable identifiers must guarantee that denotedobjects will always stay the same, without relying on external third parties and administrative processes. We analyze the role of identifiers for digital objects (IDOs), whose properties are different from, and complementary to, those of the various digital identifiers of objects (DIOs) that are today popular building blocks of software and data citation toolchains.We argue that both kinds of identifiers are needed and detail the syntax, semantics, and practical implementation of the persistent identifiers (PIDs) adopted by the Software Heritage project to reference billions of softwaresource code artifacts such as source code files, directories, and commits.