  Asset Administration Shells are trending in Industry 4.0. In February 2024,
the Industrial Digital Twin Association announced 84 and released 18 AAS
submodel specifications. As an enabler on programming level, dedicated APIs are
needed, for which, at this level of scale, automated creation is desirable. In
this paper, we present a model-driven approach, which transforms extracted
information from IDTA specifications into an intermediary meta-model and, from
there, generates API code and tests. We show we can process all current IDTA
specifications successfully leading in total to more than 50000 lines of code.
However, syntactical variations and issues in the specifications impose
obstacles that require human intervention or AI support. We also discuss
experiences that we made and lessons learned.
