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The new OMG standards form the basis for modernised, consistent and interoperable modelling – from a precise foundation (KerML), through the Systems Modeling Language (SysMLv2), to the technical interface (Systems Modeling API). This move was prompted by the limitations of UML, which is a modelling language for (object-oriented) software systems. Furthermore, SysMLv1 contained inconsistencies in semantics and offered few opportunities for reusing models or for automation. An API has also been specified that allows data from a SysMLv2 model to be queried in a structured manner. .json was adopted as the new exchange format, which finally leads to standardisation and significantly facilitates the exchange of data between previously incompatible modelling systems.

Language concepts

SysMLv2 enables the following system concepts to be modelled:

• Structure
• Behaviour
• Requirements
• Interfaces
• Parametrics
• Variability

The new language also includes textual notation.

LemonTree – Support for SysMLv2

LemonTree is already established globally as a commercial diff and merge tool, although primarily for Enterprise Architect UML / SysMLv1 models. For SysMLv2, LemonTree supports the textual notation (.sysml) and the official exchange format (.json) based on the new standard. Consequently, all modelling tools that also implement the new SysMLv2 standard and therefore offer these formats are supported.

Dr Konrad Wieland, Managing Director of LieberLieber, comments: “We welcome the introduction of SysMLv2, which enables us to exchange data with many other tools on the modelling market. However, we would like to emphasise that whilst SysMLv2 models can be processed using purely textual diff and merge tools, only LemonTree ensures that the result is consistent and valid. We will therefore be presenting the new capabilities of LemonTree 5.0 in a webinar on 24 June 2026.”

LemonTree 5.0 is coming soon

LemonTree imports the entire model content and interprets the complete dependency graph. This allows the effects of changes to be displayed in a clear and understandable way. This is particularly necessary when a complex scenario is defined in a SysMLv2 model and a change to a definition (part defs) affects many of the instances derived from it (parts). Philipp Kalenda, Head of Consulting at LieberLieber: “Even if the model is edited in parallel via a view and the text editor, the merging in LemonTree always takes place via the underlying model and not via a textual merge.”

The following features are planned for the first preview version of LemonTree 5.0 at the end of June 2026:

• Diff and merge of textual notation (.sysml files)
• Diff and merge of the SysMLv2 exchange format (.json)
• Migration from .sysml to .json and vice versa

In LemonTree, it will be possible to use Impacted Elements, the model tree and the textual notation for diff analysis. A graphical representation of the notation is already in the works.

Version control and SysMLv2

SysMLv2, with its textual notation and .sysml files, enables version control of SysMLv2 models using version control systems such as Git. However, only one view (the textual view) of the model is placed under version control and taken into account during comparison, merging and conflict resolution. Although the textual notation can be interpreted and compared on a line-by-line basis, references, dependencies and cross-references are not taken into account. Despite the similarity of the textual notation to conventional source code, a SysMLv2 model is not equivalent to it. Therefore, for collaboration using version control, a special diff and merge tool (LemonTree) is required that interprets model data as such and displays it in its graph structure.

LieberLieber in der SysMLv2 Tool Vendor Liste der OMG: https://www.omg.org/sysml/sysmlv2/sysml-tool/

Webinar on Wednesday 24 June 2026, 3.00 pm:
Model-Aware Merge: Why SysMLv2 Needs LemonTree
SysML v2 provides a modern foundation for next-generation MBSE tooling — but engineering models are more than plain text. In this webinar, we demonstrate why SysMLv2 still requires dedicated model-aware diff and merge capabilities, and how LemonTree brings professional Git-based collaboration workflows to SysMLv2 engineering. Learn how teams can understand semantic model changes, review modifications efficiently, and merge changes safely in collaborative MBSE environments. We also explore how SysMLv2 models can become part of modern CI/CD and DevOps pipelines, enabling scalable and automated engineering workflows across distributed teams.

Register for the webinar right here:
https://us06web.zoom.us/webinar/register/WN_Qo2e59RnTsqDb1dnn1tPPQ

SysMLv2: Model/Text/Graphical Representation
At present, there is a strong focus within the community on the textual notation of SysMLv2 models. However, this is equivalent to the graphical notation, which is comparable to the diagrams in SysMLv1. The focus at LemonTree is on the model-based view (graph = tree-like view), which is generated from the underlying model. This means that the comparison of models is calculated from the SysMLv2 model rather than the textual notation.