SysML v2

Getting Started with SysML v2 Projects

Choose between an LML and a SysML v2 project, create a SysML v2 project or a demo, write a first model and find your way around.

How to use it →

On this page

Overview

Holarch supports SysML v2 projects. A SysML v2 project holds one model, written in the SysML v2 textual notation and based on the OMG SysML v2 specification.

You write the model as text in the Editor. Holarch keeps the same model as elements: packages, definitions, usages and relationships. The Browser, the views and the lifecycle pages (requirements, verification, interfaces, risk, plan) all show those same elements.

This page explains the two project types, how to start a SysML v2 project, and where things are. The language itself is on SysML v2 Textual Notation. The Editor and Browser are on The Text Editor and Browser.

Concepts

Two project types

Every Holarch project is either an LML project or a SysML v2 project. You choose the type when you create the project. It stays fixed: a project changes type only through a converted copy (see Converting Between LML and SysML v2).

	LML	SysML v2
What it is for	Modeling a system in the Lifecycle Modeling Language: requirements, functions, the physical architecture, interfaces, tests, risks and the schedule. Holarch checks your work at each step.	Building a model in the SysML v2 language, as text, with standard SysML v2 concepts: packages, definitions and usages, ports, connections, actions, states and requirements.
How you build the model	The Database, forms and more than 30 diagram types.	Text in the Editor, plus views and the lifecycle pages, which write into the same text.
What you can exchange	Word, Excel, CSV, ReqIF and XMI imports; Word, Excel and diagram exports; project files.	SysML v2 text (`.sysml`) and SysML v2 JSON (see Exchanging SysML v2 Models); project files.

If you are unsure, choose LML. It has every Holarch page and diagram, and it suits people who are new to MBSE. Choose SysML v2 when your team already models in SysML v2, or exchanges models with SysML v2 tools.

The model and the text are one

A SysML v2 project has no files inside it. The model is a set of elements, and the Editor shows one text document per top-level package. When text parses, Holarch applies it to the model. When you change the model elsewhere (a view, a table, the inspector), the text changes with it. See Text and views stay in sync.

Model data and Holarch data

Some information is part of the SysML text; some is kept by Holarch next to the model.

In the text: element names, short names (requirement numbers), documentation, types, multiplicities, values, and relationships such as satisfy, verify, perform and connect.
Next to the model (Holarch data): requirement status and approvals, verification results, labels, assignees, due dates, discussion comments, view layouts, simulator settings, budgets, risks, decisions and tasks. These link to model elements by identity, so the links survive renames and moves.

Holarch data is not written into the SysML text and is not part of a .sysml export.

Definitions and usages

Most SysML v2 keywords come in two forms. A definition (part def Wheel;) describes a kind of thing. A usage (part frontWheel : Wheel;) is one use of a definition inside another element. The same pattern holds for port def/port, action def/action and requirement def/requirement. SysML v2 Textual Notation explains this in full.

How to use it

Choose a project type

Decide on the type before you create the project.

Choose LML to use the full Holarch method: the Database, the LML diagrams and guided checks at each step.
Choose SysML v2 when the model must be SysML v2 text, for example to exchange it with another SysML v2 tool.
To try SysML v2 first, open the Hybrid Car demo (next workflow but one) instead of a blank project.

Create a SysML v2 project

Open Manage Projects and click + New Project.
Under How will you model this system?, choose SysML v2.
Enter a name and click Create Project.

The project opens on Home. The chip SysML v2 shows next to the project name in the top bar and on Manage Projects. A new model is empty: Next actions on Home says Write the first package in the Editor.

Open the Hybrid Car demo

The Hybrid Car demo is a finished SysML v2 model to explore and edit.

Open Manage Projects.
Click Project Files ▾ → New Demo Project → Hybrid Car (SysML v2).

Holarch creates the project Hybrid Car (SysML v2 demo) and opens it in the Editor. The model has six top-level packages: Vehicles, VehicleRequirements, VehicleBehavior, VehicleViews, HolarchFrameworks and HybridCarArchitecture. Each one is a document in the Editor's Packages list.

The demo is your own copy. Change it freely, or create it again for a fresh start.

Open the Earth Observation Satellite demo

The Earth Observation Satellite demo is a larger model: the EO-2 mission, a 12U imaging satellite with its ground segment, in about 3,000 lines over 14 packages. Holarch's own data is filled in on top of the model, so every page has something to show.

Open Manage Projects.
Click Project Files ▾ → New Demo Project → Earth Observation Satellite (SysML v2).

Holarch creates the project Earth Observation Satellite (SysML v2 demo) and opens Home. Things to try:

Documents: open EO-2 System Requirements Specification. Its sections hold the requirements of EORequirements, live values and a verification matrix.
Budgets: the imager's mass is over its 4.0 kg allocation; the TPM Imager Mass shows the trend.
Suspect Links and TBD/TBR: changed requirements and open values to resolve.
Simulator: run the imaging pass from the imagingPassFlow view.
Baselines: compare the PDR Data Freeze baseline with the current model.
Views: the spacecraft modes, the interconnection views and the tasking sequence.

Write your first model

This workflow builds a small drone model with this text:

package Drone {
    private import ISQ::*;
    private import SI::*;

    part def Battery {
        attribute mass : MassValue = 0.4 [kg];
    }
    part def Quadcopter {
        part battery : Battery;
    }
}

Open Model → Editor, click + New Package, enter Drone and confirm. The Editor opens the new package's text.
Type the imports and members inside the package's braces, as above.
Stop typing. After a short pause the status line under the text says Applied. The model now holds the package, both part definitions, the attribute and the part, as one undo step.
Open Model → Browser and expand Drone to see the same elements as a tree.

If a line has an error, the status line says Not applied: fix line N. The model keeps its last good state until the text parses again. See Errors and drafts.

Find your way around

SysML v2 projects keep Holarch's lifecycle rail. Each group works on the SysML v2 model.

Start at Home for what needs attention, the lifecycle groups and the next actions.
Use Model → Editor to write text and Model → Browser to see the tree.
Use Needs & Requirements and Verification for requirements, verification cases and traceability.
Use Behavior, Architecture and Interfaces for the views and analysis pages.
Open the Diagrams tool at the bottom of the rail to see every view.
Press ⌘K / Ctrl+K to find any element by name, short name, qualified name (Vehicles::Car) or documentation text.

Worked example: explore the Hybrid Car

This walk-through uses the Hybrid Car demo.

Create the demo (see Open the Hybrid Car demo). The Editor opens on Vehicles.
Find part def Car. It has the parts body, powertrain, frontAxle, rearAxle and spare : Wheel [0..1].
⌘ / Ctrl-click Powertrain in part powertrain : Powertrain;. The cursor jumps to part def Powertrain, with its parts tank, engine, motor, battery, transmission and controller, and interfaces such as interface fuel : FuelLine connect tank.fuelOut to engine.fuelIn;.
Point at MassValue in attribute mass : MassValue;. A card shows its kind and qualified name from the standard library.
Open Model → Browser. Type sedan in Filter by name. The tree shows sedan under fleet in Vehicles. Select it: the inspector shows Kind part, Typed by Car and the qualified name Vehicles::fleet::sedan.
Open Home. The Lifecycle card of Needs & Requirements counts the model's requirements; Needs attention shows the suspect links, overdue TBDs and high risks of the model.
Open Needs & Requirements → Requirements. The rows include VR-1.1 sedanMass, a requirement usage whose number is its short name <'VR-1.1'>.
Open the Diagrams tool and open driveCycleFlow, the action flow view of DriveCycle. Rename an action there and return to the Editor: VehicleBehavior shows the new name.

Tips and common mistakes

Start from the demo. Copying patterns from the Hybrid Car text is the fastest way to learn the notation.
Import the units. 5 [kg] needs SI (and MassValue needs ISQ) to be visible. Add private import ISQ::*; and private import SI::*; to the package.
Keep one model per project. Split a large model into several top-level packages; each is its own document in the Editor.
Choosing the wrong type. The type cannot be switched in place. Make a converted copy from Manage Projects (⋯ → Make an LML Copy… or Make a SysML v2 Copy…).
Expecting status in the text. Requirement status, verification results and labels are Holarch data. They do not appear in the text or in a .sysml export.

The rail in SysML v2 projects

Group	Pages
Home	Needs attention, Lifecycle, Next actions and the other Home panels
Needs & Requirements	Documents, Requirements, Quality, TBD/TBR, Suspect Links, Approvals
Model	Editor, Browser, Import and Export
Behavior	Functional Analysis, Action Flows, FFBD, State Machines, Sequences, Simulator
Architecture	Parts, General Views, Interconnection Views, Hierarchy, Budgets & TPMs
Interfaces	Interface Register, ICDs, N² Diagrams, Items & I/O
Verification	RVTM, Verification Cases, Traceability Matrix, Model Checks
Risk & Decisions	Risk Register, Risk Diagrams, Trade Studies, Decisions
Plan & Deliver	My Work, SE Process, Project Management, Charts, Whiteboards, Change Requests, Baselines & Versions, Review Packages, Presentations
Frameworks	DoDAF, UAF

The Diagrams tool and the Trash sit at the bottom of the rail. Standard Library is in the rail tools; in LML projects this place holds the Schema. Pages that do not apply to SysML v2 projects are not shown.

The pages are described on SysML v2 Views, Requirements and Verification in SysML v2 Projects, Evaluation, Units and Analysis in SysML v2 Projects and Holarch Features in SysML v2 Projects.

Home

Home is the same page as in LML projects (see Home): Needs attention (suspect links, overdue TBDs, failing tests, TPM breaches, high risks, model checks, save status), a Lifecycle card per rail group, and the panels such as Next actions, SE Process gate and Milestones. The counts come from the SysML v2 model and the Holarch data next to it. ✦ Write Project Brief is not offered in SysML v2 projects.

The rail groups show the same problem badges, and each group's overview page lists what needs attention and its numbers.
+ Add panel → Model contents shows Packages (with the number of top-level packages), Definitions, Usages, Relationships and Requirements (n not satisfied · n not verified), misplaced elements when elements have lost their owner, and Recent changes: the latest model changes (created, changed, moved, deleted or restored) with the element's kind and the time.

Ask AI

Ask AI answers questions about the SysML v2 language and about using Holarch, from Help and Docs. On the Individual and Team plans, and with your own or your organization's AI key, it also answers questions about the open model and proposes changes, which open for review before they apply. See Ask AI.

Not yet available

Writing to Holarch through the Systems Modeling API: other tools read the current model only (see The API and MCP in SysML v2 Projects).
Running state machines in the Simulator. Action flows run; see Evaluation, Units and Analysis in SysML v2 Projects.
Editing the language: the standard library is read-only.

SysML v2 Textual Notation lists the supported language in detail.

Messages

Message	Meaning
The model is empty	The project has no elements. Click + New Package, then write its members in the Editor.
Not applied: fix line N.	The text has an error on line N. The model keeps its last good state until the text parses.
View only: ask an owner for edit access.	You have view access to the project. The text and pages are read-only.

Limits

The project type is fixed at creation.
One model per project.
A text document larger than 8 MB is not checked; split it into several packages.

SysML® and OMG® are registered trademarks of Object Management Group, Inc. in the United States and other countries.