Level 1: Ad-Hoc Usage
At this level, an organization has ad hoc or informal practices for managing open source software. There is no formal policy or process in place for managing open source software, and its use is left up to individual developers. The organization has limited visibility into open source use and does not keep track of the software used.
Further Reading
The TODO Group Maturity Model refers to this level as "Stage 0: Adopting Open Source Ad Hoc":
Today, almost all organizations use OSS. How they adopt and initially use it varies. They may use OSS as a building block or library in a product or tool or a key part of a vendor’s product stack or supporting the vendor’s service offering. Developers may use OSS for rapid prototyping or for microservices and small applications. Developers also frequently adopt OSS development tools such as integrated development environments (IDEs), or tools built on top of open source like GitHub and GitLab.
In The State of Enterprise Open Source, RedHat report that 90% of IT Leaders are using enterprise open source. This means that at least Level 1 open source usage is endemic in industry.
The OW2 Open Source Good Governance Initiative refers to this level as the "Usage Goal" and provides a number of links to articles expounding the value of open source usage. It defines this level:
[This level] is about using OSS and competences in using OSS. It covers technical ability and experience with OSS. Plus developing some understanding and awareness of OSS.