SysML v2 — Ran Wei

Module 8: Variability & Configuration

How to define variation points, declare alternative variants, and configure product lines — enabling a single model to capture an entire family of system configurations.

★

KerML → SysML: Variability Concepts

SysML v2 variability is built on KerML’s usage variation and variant membership mechanisms. A variation usage declares a point of variability — a feature that must be bound to exactly one of its allowed alternatives. Each variant within that variation is a distinct membership option. At the KerML level, these are modelled through feature membership and subsetting relationships on usages.

Table 0 — Module 8 SysML v2 (L2) concepts mapped to KerML (L1) origins
SysML v2 concept (L2)	Underlying KerML construct (L1)	What SysML adds
`variation` (on a usage)	Usage with `isVariation = true`	Marks a feature as a variation point; must be resolved to exactly one variant in any complete configuration
`variant`	`VariantMembership` (a kind of `OwningMembership`)	Declares a named alternative within a variation point; each variant subsets the variation usage
`variation part def`	`PartDefinition` with `isVariation = true`	A definition whose usages are inherently variation points — every usage must be resolved
`variant` (in a variation def)	`VariantMembership` owning a usage	A usage that serves as one option within a variation definition
Configuration binding	`BindingConnector` resolving a variation to a specific variant	Fixes the choice; produces a fully resolved product instance
`filter` expression	`FilterExpression` (a Boolean expression on metadata)	Selects elements from a package or namespace based on metadata criteria
Product line package	`Package` with mixed variation/non-variation content	Organises shared platform elements alongside variation points for a product family

NOTE

In KerML, isVariation is a Boolean property on any Usage. When set to true, the usage becomes a variation point. Its owned members with VariantMembership are the allowed choices. SysML v2 provides the variation and variant keywords as syntactic sugar for this mechanism.

Variation Points

KerML origin: variation → Usage with isVariation = true

A variation point is a feature in a model that represents a choice — a place where different configurations may differ. In SysML v2, you declare a variation point by prefixing a usage with the variation keyword. The variation usage itself is not a concrete element; it is a placeholder that must be resolved to one of its variants in any complete configuration.

ANALOGY

Think of a restaurant menu. The “Main Course” slot on the menu is a variation point — every diner must choose exactly one option. The individual dishes (steak, fish, pasta) are variants. The menu defines the structure; each diner’s order is a configuration.

Variation on part usages

The most common form of variation applies to part usages within a part definition. The variation keyword declares that the feature is a point of variability, and variant members declare the allowed alternatives:


1 part def Vehicle {
2     part engine : Engine;
3 
4     // Variation point: transmission type
5     variation part transmission : Transmission {
6         variant part manual    : ManualTransmission;
7         variant part automatic : AutomaticTransmission;
8         variant part cvt       : CVTTransmission;
9     }
10 }

In this model, every instance of Vehicle must have exactly one transmission — either manual, automatic, or CVT. The variation point is not optional; it mandates a choice.

Variation on attribute usages

Variation points are not limited to parts. You can apply them to attributes, ports, or any other usage kind:


1 part def Display {
2     // Variation point: screen resolution
3     variation attribute resolution : ScreenResolution {
4         variant attribute hd   : HD;    // 1280x720
5         variant attribute fhd  : FHD;   // 1920x1080
6         variant attribute uhd  : UHD;   // 3840x2160
7     }
8 }

PITFALL

A variation point must contain at least one variant member. Declaring a variation usage with no variants is a semantic error — there is no choice to make. Tooling should flag this as incomplete.

Variant Definitions

KerML origin: variant → VariantMembership (a kind of OwningMembership)

A variant is a concrete alternative within a variation point. Each variant is a fully specified element — it carries its own features, constraints, and sub-structure. When a configuration selects a variant, that variant’s full definition replaces the variation point in the resolved model.

Inline variant definitions

Variants can be defined inline within the variation point, carrying their own unique features:


1 part def Powertrain {
2     variation part motorType : Motor {
3         variant part ice : ICEMotor {
4             attribute displacement : ISQ::VolumeValue;
5             attribute cylinders    : ScalarValues::Integer;
6         }
7         variant part electric : ElectricMotor {
8             attribute peakPower   : ISQ::PowerValue;
9             attribute batteryCapacity : ISQ::EnergyValue;
10         }
11         variant part hybrid : HybridMotor {
12             attribute displacement : ISQ::VolumeValue;
13             attribute peakPower   : ISQ::PowerValue;
14         }
15     }
16 }

Referencing external variant definitions

Variants can also reference separately defined part definitions. This is useful when the same variant appears in multiple variation points across the model:


1 part def ManualTransmission :> Transmission {
2     attribute gearCount : ScalarValues::Integer;
3 }
4 
5 part def AutomaticTransmission :> Transmission {
6     attribute modes : DriveMode[1..*];
7 }
8 
9 part def Vehicle {
10     // Variants reference externally defined part defs
11     variation part transmission : Transmission {
12         variant part manual    : ManualTransmission;
13         variant part automatic : AutomaticTransmission;
14     }
15 }

Variation definitions

You can also mark an entire definition as a variation using variation part def. This means the definition itself is abstract — it cannot be instantiated directly but must be resolved to one of its variant members:


1 variation part def DriveMode {
2     variant eco   : EcoMode;
3     variant sport : SportMode;
4     variant normal: NormalMode;
5 }

NOTE

The distinction between variation on a usage and variation on a definition is important. A variation usage is a specific feature that must be resolved in context. A variation definition declares that the type itself is a variation — every usage of that definition inherits the variation point semantics.

Configuration Management

KerML origin: Configuration binding → BindingConnector resolving a variation to a specific variant

A configuration is a concrete resolution of all variation points in a model. It selects exactly one variant for each variation point, producing a fully specified product instance. In SysML v2, configurations are modelled by specialising the product definition and binding each variation usage to its chosen variant.

Creating a configuration by specialisation

The standard pattern is to create a new part definition or usage that specialises the variable product and binds each variation point:


1 // Base product with variation points
2 part def Vehicle {
3     part engine : Engine;
4     variation part transmission : Transmission {
5         variant part manual    : ManualTransmission;
6         variant part automatic : AutomaticTransmission;
7     }
8     variation part infotainment : Infotainment {
9         variant part basic   : BasicInfotainment;
10         variant part premium : PremiumInfotainment;
11     }
12 }
13 
14 // Configuration: Sport Edition
15 part def SportEdition :> Vehicle {
16     // Resolve transmission to manual
17     part transmission redefines Vehicle::transmission = manual;
18     // Resolve infotainment to premium
19     part infotainment redefines Vehicle::infotainment = premium;
20 }
21 
22 // Configuration: Economy Edition
23 part def EconomyEdition :> Vehicle {
24     part transmission redefines Vehicle::transmission = automatic;
25     part infotainment redefines Vehicle::infotainment = basic;
26 }

Partial configurations

Not every configuration must resolve all variation points. A partial configuration resolves some variation points while leaving others open. This is useful for modelling product tiers or regional variants where some choices are fixed but others remain flexible:


1 // Partial configuration: European variant (fixes transmission, leaves infotainment open)
2 part def EuropeanVehicle :> Vehicle {
3     part transmission redefines Vehicle::transmission = manual;
4     // infotainment variation point remains unresolved
5 }
6 
7 // Full configuration: European Sport (resolves remaining variation)
8 part def EuropeanSport :> EuropeanVehicle {
9     part infotainment redefines Vehicle::infotainment = premium;
10 }

TIP

Use partial configurations to build a layered configuration hierarchy. Start with a base product, create regional or tier-level partial configurations, and then create fully resolved configurations at the leaf level. This mirrors how automotive OEMs manage product lines in practice.

Filtering & Selection

KerML origin: filter → FilterExpression (Boolean expression on metadata)

Filter expressions provide a query mechanism for selecting elements from a namespace based on metadata criteria. Unlike direct variant binding, filters work across packages and can select multiple elements simultaneously. They are especially powerful when combined with metadata annotations.

Basic filter syntax

A filter expression is a Boolean predicate applied to elements in a package. Only elements satisfying the predicate are included in the filtered view:


1 // Metadata for tagging elements
2 metadata def Region {
3     attribute name : ScalarValues::String;
4 }
5 
6 metadata def Tier {
7     attribute level : ScalarValues::String;
8 }
9 
10 package AllFeatures {
11     part heatedSeats : HeatedSeats {
12         @Region { name = "EU"; }
13         @Tier { level = "premium"; }
14     }
15     part airCon : AirConditioning {
16         @Region { name = "ALL"; }
17         @Tier { level = "basic"; }
18     }
19     part sunroof : PanoramicSunroof {
20         @Region { name = "US"; }
21         @Tier { level = "premium"; }
22     }
23 }

Applying filter expressions

Filter expressions select elements from a package based on their metadata. The filtered package acts as a view — it does not duplicate elements but provides a scoped subset:


1 // Select only premium-tier features
2 package PremiumFeatures filter Region::name == "ALL" or Tier::level == "premium";
3 
4 // Select only EU-region features
5 package EUFeatures filter Region::name == "EU" or Region::name == "ALL";

NOTE

Filter expressions operate on metadata annotations. They do not modify the underlying model — they produce a view of the model that includes only matching elements. This is conceptually similar to a database query: the data is unchanged, but the result set is narrowed.

Combining filters with variations

Filters and variation points are complementary mechanisms. Variation points define mandatory choices (you must pick one). Filters define optional inclusion (include if criteria are met). A well-designed product line uses both:

Variation points for structural alternatives (engine type, body style)
Filters for feature packages (comfort options, regional compliance features)

PITFALL

Do not use filters as a substitute for variation points. A filter selects from an existing set; a variation point declares a mandatory choice. If every product must have exactly one of several alternatives, use variation/variant. If a feature is conditionally included based on metadata, use filter.

Product Line Modelling

KerML origin: Product line → Package with mixed variation/non-variation content

A product line is a family of products that share a common platform but differ in specific features. SysML v2 supports product line modelling through a combination of shared definitions (the platform), variation points (the configurable aspects), and configurations (the resolved products).

Platform + variant strategy

The recommended pattern separates the model into three layers:

Platform package — shared definitions, invariant structure, common constraints
Variability package — variation points and variant definitions
Configuration package — fully resolved products that bind all variation points


1 package Platform {
2     // Shared across all products
3     part def Chassis { attribute wheelbase : ISQ::LengthValue; }
4     part def BrakeSystem { part frontBrakes : DiscBrake; part rearBrakes : DiscBrake; }
5     part def SteeringSystem { attribute ratio : ScalarValues::Real; }
6 }
7 
8 package Variability {
9     private import Platform::*;
10 
11     part def ProductVehicle {
12         part chassis  : Chassis;       // from platform (invariant)
13         part brakes   : BrakeSystem;   // from platform (invariant)
14         part steering : SteeringSystem; // from platform (invariant)
15 
16         // Variable aspects
17         variation part body : BodyStyle {
18             variant part sedan : SedanBody;
19             variant part suv   : SUVBody;
20             variant part truck : TruckBody;
21         }
22         variation part powertrain : Powertrain {
23             variant part petrol   : PetrolPowertrain;
24             variant part diesel   : DieselPowertrain;
25             variant part electric : ElectricPowertrain;
26         }
27     }
28 }
29 
30 package Configurations {
31     private import Variability::*;
32 
33     part def SedanPetrol :> ProductVehicle {
34         part body redefines ProductVehicle::body = sedan;
35         part powertrain redefines ProductVehicle::powertrain = petrol;
36     }
37 
38     part def SUVElectric :> ProductVehicle {
39         part body redefines ProductVehicle::body = suv;
40         part powertrain redefines ProductVehicle::powertrain = electric;
41     }
42 }

Constraint propagation across variants

Constraints defined on the platform or base product apply to all configurations. Variant-specific constraints can be added at the variant level:


1 part def ProductVehicle {
2     // Platform constraint: applies to ALL configurations
3     assert constraint maxWeight {
4         chassis.totalMass <= 2500[kg]
5     }
6 
7     variation part body : BodyStyle {
8         variant part truck : TruckBody {
9             // Variant-specific constraint: only applies when truck is selected
10             assert constraint towingCapacity {
11                 payloadCapacity >= 1000[kg]
12             }
13         }
14     }
15 }

TIP

The three-layer pattern (platform, variability, configuration) scales well. The platform package can be maintained by a platform engineering team, the variability package by product management, and the configuration package by specific product teams. Each layer imports from the one below.

Complete Worked Example

The following model integrates all concepts from this module: a vehicle product line with sedan, SUV, and truck variants sharing a common platform, each with powertrain and feature-level variability, metadata-driven filtering, and fully resolved configurations.


1 package VehicleProductLine {
2     private import ISQ::*;
3     private import SI::*;
4     private import ScalarValues::*;
5 
6     // ── Metadata for filtering ──────────────────────────────
7     metadata def MarketRegion {
8         attribute region : String;
9     }
10     metadata def FeatureTier {
11         attribute tier : String;
12     }
13 
14     // ── Shared platform ─────────────────────────────────────
15     part def Chassis {
16         attribute wheelbase : LengthValue;
17         attribute curbWeight : MassValue;
18     }
19     part def BrakeSystem {
20         part frontBrakes : DiscBrake;
21         part rearBrakes  : DiscBrake;
22         part abs : ABSController;
23     }
24     part def SteeringSystem {
25         attribute steeringRatio : Real;
26     }
27 
28     // ── Body style variants ──────────────────────────────────
29     part def BodyStyle;
30     part def SedanBody :> BodyStyle {
31         attribute doorCount   : Integer = 4;
32         attribute trunkVolume : VolumeValue;
33     }
34     part def SUVBody :> BodyStyle {
35         attribute doorCount     : Integer = 5;
36         attribute groundClearance : LengthValue;
37         attribute roofRails     : Boolean = true;
38     }
39     part def TruckBody :> BodyStyle {
40         attribute doorCount      : Integer = 4;
41         attribute bedLength      : LengthValue;
42         attribute payloadCapacity : MassValue;
43     }
44 
45     // ── Powertrain variants ──────────────────────────────────
46     part def Powertrain;
47     part def PetrolPowertrain :> Powertrain {
48         attribute displacement : VolumeValue;
49         attribute cylinders    : Integer;
50         attribute maxPower     : PowerValue;
51     }
52     part def DieselPowertrain :> Powertrain {
53         attribute displacement : VolumeValue;
54         attribute maxTorque    : ForceValue;
55     }
56     part def ElectricPowertrain :> Powertrain {
57         attribute batteryCapacity : EnergyValue;
58         attribute range           : LengthValue;
59         attribute chargePower     : PowerValue;
60     }
61 
62     // ── Optional feature packages (metadata-tagged) ─────────
63     package FeatureCatalog {
64         part heatedSeats : HeatedSeats {
65             @MarketRegion { region = "ALL"; }
66             @FeatureTier { tier = "premium"; }
67         }
68         part adaptiveCruise : AdaptiveCruiseControl {
69             @MarketRegion { region = "ALL"; }
70             @FeatureTier { tier = "premium"; }
71         }
72         part towHitch : TowHitch {
73             @MarketRegion { region = "US"; }
74             @FeatureTier { tier = "basic"; }
75         }
76         part headlightWashers : HeadlightWashers {
77             @MarketRegion { region = "EU"; }
78             @FeatureTier { tier = "basic"; }
79         }
80     }
81 
82     // ── Base product with variation points ───────────────────
83     part def Vehicle {
84         // Platform (invariant across all configurations)
85         part chassis  : Chassis;
86         part brakes   : BrakeSystem;
87         part steering : SteeringSystem;
88 
89         // Variation point 1: body style
90         variation part body : BodyStyle {
91             variant part sedan : SedanBody;
92             variant part suv   : SUVBody;
93             variant part truck : TruckBody;
94         }
95 
96         // Variation point 2: powertrain
97         variation part powertrain : Powertrain {
98             variant part petrol   : PetrolPowertrain;
99             variant part diesel   : DieselPowertrain;
100             variant part electric : ElectricPowertrain;
101         }
102 
103         // Platform constraint: all variants must satisfy
104         assert constraint maxGrossWeight {
105             chassis.curbWeight <= 3000[kg]
106         }
107     }
108 
109     // ── Filtered feature views ───────────────────────────────
110     package PremiumFeatures filter FeatureTier::tier == "premium";
111     package USFeatures filter MarketRegion::region == "US"
112                             or MarketRegion::region == "ALL";
113     package EUFeatures filter MarketRegion::region == "EU"
114                             or MarketRegion::region == "ALL";
115 
116     // ── Fully resolved configurations ────────────────────────
117     part def SedanPetrolUS :> Vehicle {
118         part body redefines Vehicle::body = sedan;
119         part powertrain redefines Vehicle::powertrain = petrol;
120         // Include US-market features from the filtered view
121     }
122 
123     part def SUVElectricEU :> Vehicle {
124         part body redefines Vehicle::body = suv;
125         part powertrain redefines Vehicle::powertrain = electric;
126         // Include EU-market features from the filtered view
127     }
128 
129     part def TruckDieselUS :> Vehicle {
130         part body redefines Vehicle::body = truck;
131         part powertrain redefines Vehicle::powertrain = diesel;
132 
133         // Truck-specific constraint override
134         assert constraint towRating {
135             body.payloadCapacity >= 1500[kg]
136         }
137     }
138 }

This model demonstrates: a shared platform (chassis, brakes, steering), two variation points (body style, powertrain) with three variants each, metadata-tagged optional features with filter expressions for market regions and tiers, platform-level constraints that apply to all configurations, variant-specific constraints (truck tow rating), and three fully resolved configurations targeting different market segments.

Module Summary

Table — Module 8 concepts and their KerML origins
SysML v2 concept	KerML origin	Key rule
`variation` (on usage)	Usage with `isVariation = true`	Marks a feature as a variation point; must be resolved to exactly one variant
`variant`	`VariantMembership`	Declares one allowed alternative within a variation point
`variation part def`	`PartDefinition` with `isVariation = true`	The definition itself is a variation; every usage inherits variation semantics
Configuration binding	`BindingConnector`	Resolves a variation usage to a specific variant via `redefines`
Partial configuration	Specialisation with some variations unresolved	Fixes some choices, leaves others open for further specialisation
`filter` expression	`FilterExpression`	Selects elements from a namespace based on metadata criteria; produces a view
Product line package	Package with mixed content	Three-layer pattern: platform + variability + configurations
Metadata tagging	Metadata annotations	Annotates elements with region, tier, or other selection criteria for filtering

Up Next

Module 9 — Verification & Validation — How to define verification cases, bind them to requirements, model verification methods, and integrate V&V into the systems engineering lifecycle.

1	part def Vehicle {
2	part engine : Engine;
3
4	// Variation point: transmission type
5	variation part transmission : Transmission {
6	variant part manual : ManualTransmission;
7	variant part automatic : AutomaticTransmission;
8	variant part cvt : CVTTransmission;
9	}
10	}

1	part def Display {
2	// Variation point: screen resolution
3	variation attribute resolution : ScreenResolution {
4	variant attribute hd : HD; // 1280x720
5	variant attribute fhd : FHD; // 1920x1080
6	variant attribute uhd : UHD; // 3840x2160
7	}
8	}

1	part def Powertrain {
2	variation part motorType : Motor {
3	variant part ice : ICEMotor {
4	attribute displacement : ISQ::VolumeValue;
5	attribute cylinders : ScalarValues::Integer;
6	}
7	variant part electric : ElectricMotor {
8	attribute peakPower : ISQ::PowerValue;
9	attribute batteryCapacity : ISQ::EnergyValue;
10	}
11	variant part hybrid : HybridMotor {
12	attribute displacement : ISQ::VolumeValue;
13	attribute peakPower : ISQ::PowerValue;
14	}
15	}
16	}

1	part def ManualTransmission :> Transmission {
2	attribute gearCount : ScalarValues::Integer;
3	}
4
5	part def AutomaticTransmission :> Transmission {
6	attribute modes : DriveMode[1..*];
7	}
8
9	part def Vehicle {
10	// Variants reference externally defined part defs
11	variation part transmission : Transmission {
12	variant part manual : ManualTransmission;
13	variant part automatic : AutomaticTransmission;
14	}
15	}

1	variation part def DriveMode {
2	variant eco : EcoMode;
3	variant sport : SportMode;
4	variant normal: NormalMode;
5	}

1	// Base product with variation points
2	part def Vehicle {
3	part engine : Engine;
4	variation part transmission : Transmission {
5	variant part manual : ManualTransmission;
6	variant part automatic : AutomaticTransmission;
7	}
8	variation part infotainment : Infotainment {
9	variant part basic : BasicInfotainment;
10	variant part premium : PremiumInfotainment;
11	}
12	}
13
14	// Configuration: Sport Edition
15	part def SportEdition :> Vehicle {
16	// Resolve transmission to manual
17	part transmission redefines Vehicle::transmission = manual;
18	// Resolve infotainment to premium
19	part infotainment redefines Vehicle::infotainment = premium;
20	}
21
22	// Configuration: Economy Edition
23	part def EconomyEdition :> Vehicle {
24	part transmission redefines Vehicle::transmission = automatic;
25	part infotainment redefines Vehicle::infotainment = basic;
26	}

1	// Partial configuration: European variant (fixes transmission, leaves infotainment open)
2	part def EuropeanVehicle :> Vehicle {
3	part transmission redefines Vehicle::transmission = manual;
4	// infotainment variation point remains unresolved
5	}
6
7	// Full configuration: European Sport (resolves remaining variation)
8	part def EuropeanSport :> EuropeanVehicle {
9	part infotainment redefines Vehicle::infotainment = premium;
10	}

1	// Metadata for tagging elements
2	metadata def Region {
3	attribute name : ScalarValues::String;
4	}
5
6	metadata def Tier {
7	attribute level : ScalarValues::String;
8	}
9
10	package AllFeatures {
11	part heatedSeats : HeatedSeats {
12	@Region { name = "EU"; }
13	@Tier { level = "premium"; }
14	}
15	part airCon : AirConditioning {
16	@Region { name = "ALL"; }
17	@Tier { level = "basic"; }
18	}
19	part sunroof : PanoramicSunroof {
20	@Region { name = "US"; }
21	@Tier { level = "premium"; }
22	}
23	}

1	// Select only premium-tier features
2	package PremiumFeatures filter Region::name == "ALL" or Tier::level == "premium";
3
4	// Select only EU-region features
5	package EUFeatures filter Region::name == "EU" or Region::name == "ALL";

1	package Platform {
2	// Shared across all products
3	part def Chassis { attribute wheelbase : ISQ::LengthValue; }
4	part def BrakeSystem { part frontBrakes : DiscBrake; part rearBrakes : DiscBrake; }
5	part def SteeringSystem { attribute ratio : ScalarValues::Real; }
6	}
7
8	package Variability {
9	private import Platform::*;
10
11	part def ProductVehicle {
12	part chassis : Chassis; // from platform (invariant)
13	part brakes : BrakeSystem; // from platform (invariant)
14	part steering : SteeringSystem; // from platform (invariant)
15
16	// Variable aspects
17	variation part body : BodyStyle {
18	variant part sedan : SedanBody;
19	variant part suv : SUVBody;
20	variant part truck : TruckBody;
21	}
22	variation part powertrain : Powertrain {
23	variant part petrol : PetrolPowertrain;
24	variant part diesel : DieselPowertrain;
25	variant part electric : ElectricPowertrain;
26	}
27	}
28	}
29
30	package Configurations {
31	private import Variability::*;
32
33	part def SedanPetrol :> ProductVehicle {
34	part body redefines ProductVehicle::body = sedan;
35	part powertrain redefines ProductVehicle::powertrain = petrol;
36	}
37
38	part def SUVElectric :> ProductVehicle {
39	part body redefines ProductVehicle::body = suv;
40	part powertrain redefines ProductVehicle::powertrain = electric;
41	}
42	}

1	part def ProductVehicle {
2	// Platform constraint: applies to ALL configurations
3	assert constraint maxWeight {
4	chassis.totalMass <= 2500[kg]
5	}
6
7	variation part body : BodyStyle {
8	variant part truck : TruckBody {
9	// Variant-specific constraint: only applies when truck is selected
10	assert constraint towingCapacity {
11	payloadCapacity >= 1000[kg]
12	}
13	}
14	}
15	}

1	package VehicleProductLine {
2	private import ISQ::*;
3	private import SI::*;
4	private import ScalarValues::*;
5
6	// ── Metadata for filtering ──────────────────────────────
7	metadata def MarketRegion {
8	attribute region : String;
9	}
10	metadata def FeatureTier {
11	attribute tier : String;
12	}
13
14	// ── Shared platform ─────────────────────────────────────
15	part def Chassis {
16	attribute wheelbase : LengthValue;
17	attribute curbWeight : MassValue;
18	}
19	part def BrakeSystem {
20	part frontBrakes : DiscBrake;
21	part rearBrakes : DiscBrake;
22	part abs : ABSController;
23	}
24	part def SteeringSystem {
25	attribute steeringRatio : Real;
26	}
27
28	// ── Body style variants ──────────────────────────────────
29	part def BodyStyle;
30	part def SedanBody :> BodyStyle {
31	attribute doorCount : Integer = 4;
32	attribute trunkVolume : VolumeValue;
33	}
34	part def SUVBody :> BodyStyle {
35	attribute doorCount : Integer = 5;
36	attribute groundClearance : LengthValue;
37	attribute roofRails : Boolean = true;
38	}
39	part def TruckBody :> BodyStyle {
40	attribute doorCount : Integer = 4;
41	attribute bedLength : LengthValue;
42	attribute payloadCapacity : MassValue;
43	}
44
45	// ── Powertrain variants ──────────────────────────────────
46	part def Powertrain;
47	part def PetrolPowertrain :> Powertrain {
48	attribute displacement : VolumeValue;
49	attribute cylinders : Integer;
50	attribute maxPower : PowerValue;
51	}
52	part def DieselPowertrain :> Powertrain {
53	attribute displacement : VolumeValue;
54	attribute maxTorque : ForceValue;
55	}
56	part def ElectricPowertrain :> Powertrain {
57	attribute batteryCapacity : EnergyValue;
58	attribute range : LengthValue;
59	attribute chargePower : PowerValue;
60	}
61
62	// ── Optional feature packages (metadata-tagged) ─────────
63	package FeatureCatalog {
64	part heatedSeats : HeatedSeats {
65	@MarketRegion { region = "ALL"; }
66	@FeatureTier { tier = "premium"; }
67	}
68	part adaptiveCruise : AdaptiveCruiseControl {
69	@MarketRegion { region = "ALL"; }
70	@FeatureTier { tier = "premium"; }
71	}
72	part towHitch : TowHitch {
73	@MarketRegion { region = "US"; }
74	@FeatureTier { tier = "basic"; }
75	}
76	part headlightWashers : HeadlightWashers {
77	@MarketRegion { region = "EU"; }
78	@FeatureTier { tier = "basic"; }
79	}
80	}
81
82	// ── Base product with variation points ───────────────────
83	part def Vehicle {
84	// Platform (invariant across all configurations)
85	part chassis : Chassis;
86	part brakes : BrakeSystem;
87	part steering : SteeringSystem;
88
89	// Variation point 1: body style
90	variation part body : BodyStyle {
91	variant part sedan : SedanBody;
92	variant part suv : SUVBody;
93	variant part truck : TruckBody;
94	}
95
96	// Variation point 2: powertrain
97	variation part powertrain : Powertrain {
98	variant part petrol : PetrolPowertrain;
99	variant part diesel : DieselPowertrain;
100	variant part electric : ElectricPowertrain;
101	}
102
103	// Platform constraint: all variants must satisfy
104	assert constraint maxGrossWeight {
105	chassis.curbWeight <= 3000[kg]
106	}
107	}
108
109	// ── Filtered feature views ───────────────────────────────
110	package PremiumFeatures filter FeatureTier::tier == "premium";
111	package USFeatures filter MarketRegion::region == "US"
112	or MarketRegion::region == "ALL";
113	package EUFeatures filter MarketRegion::region == "EU"
114	or MarketRegion::region == "ALL";
115
116	// ── Fully resolved configurations ────────────────────────
117	part def SedanPetrolUS :> Vehicle {
118	part body redefines Vehicle::body = sedan;
119	part powertrain redefines Vehicle::powertrain = petrol;
120	// Include US-market features from the filtered view
121	}
122
123	part def SUVElectricEU :> Vehicle {
124	part body redefines Vehicle::body = suv;
125	part powertrain redefines Vehicle::powertrain = electric;
126	// Include EU-market features from the filtered view
127	}
128
129	part def TruckDieselUS :> Vehicle {
130	part body redefines Vehicle::body = truck;
131	part powertrain redefines Vehicle::powertrain = diesel;
132
133	// Truck-specific constraint override
134	assert constraint towRating {
135	body.payloadCapacity >= 1500[kg]
136	}
137	}
138	}