## Background Data and interaction models of IoT devices today exhibit unneeded diversity between different industry ecosystem standards development organizations (SDOs), hindering interoperability across these ecosystems with little discernible benefit from the diversity. Early in 2019, One Data Model (OneDM, https://onedm.org) was started to bring several IoT SDOs and IoT device and platform vendors together under a broad, multi-party liaison agreement, with a goal of arriving at a common set of data and interaction models that describe IoT devices. Ideally, for every class of IoT device, there is just a single model selected/created by the participating organizations, which everyone can adopt. As a common language for writing down these models, the Semantic Definition Format (SDF) was created, which can represent IoT Things, their composition from reusable Objects, their Interaction Affordances (Properties, Actions, Events), and the data models relevant to describe these Affordances. SDF represents these models in JSON, enabling re-use of specification formats such as CDDL (RFC8610) and the formats proposed at json-schema.org and their tooling, for describing both the SDF format itself and the structure of the data to be modelled in SDF. Some 200 models in SDF format have been contributed by participating ecosystems; new models are being submitted continually. Version 1.0 of the SDF specification was published on the OneDM github repository and as draft-onedm-t2trg-sdf. OneDM is now focusing on consolidating the body of submitted models and developing processes for arriving at harmonized models that span different industry ecosystems in a common way; they look to the IETF for further development of SDF 1.0 into a high-quality specification. ## The ASDF Working Group The objective of the ASDF working group is to develop SDF to an IETF-quality specification for Thing Interaction and Data Modelling, working with experts from OneDM and its contributing organizations. On the way to that specification, further functionality requirements will be addressed that emerge in the usage of SDF for model harmonization. The ASDF WG will work closely with the CBOR WG, home of the CDDL specification. It will also engage the still active mailing list of the concluded JSON WG. Recent proposals to form an IRTF formal description techniques (FDT) Research Group might lead to another collaboration partner. The Thing-to-Thing Research Group (T2TRG) and its WISHI program can be instrumental in engaging researchers and other SDOs in this space, such as W3C Web of Things, which is working on Thing Description Templates and related specifications. The working group has one deliverable: the SDF specification. It is not currently foreseen that this will be split into multiple documents, but that is also not excluded. The working group might choose to develop the specification by evolving it in a regular rhythm, with a new "Implementation Draft" available about bi-monthly.