diff --git a/node/eslint.config.js b/node/eslint.config.js
index 7c4cecb..0c3d7b4 100644
--- a/node/eslint.config.js
+++ b/node/eslint.config.js
@@ -2,13 +2,23 @@ import js from '@eslint/js'
 import globals from 'globals'
 import tseslint from 'typescript-eslint'
 import { defineConfig } from 'eslint/config'
+import simpleImportSort from 'eslint-plugin-simple-import-sort'
 
 export default defineConfig([
     {
         files: ['**/*.ts'],
-        plugins: { js },
+        plugins: { js, 'simple-import-sort': simpleImportSort },
         extends: ['js/recommended'],
-        languageOptions: { globals: { ...globals.browser, ...globals.node } },
+        languageOptions: {
+            globals: { ...globals.browser, ...globals.node },
+            parserOptions: {
+                projectService: true,
+            },
+        },
+        rules: {
+            'simple-import-sort/imports': 'error',
+            'simple-import-sort/exports': 'error',
+        },
     },
-    tseslint.configs.recommended,
+    tseslint.configs.recommendedTypeChecked,
 ])
diff --git a/node/src/builders/collection.ts b/node/src/builders/collection.ts
new file mode 100644
index 0000000..c160383
--- /dev/null
+++ b/node/src/builders/collection.ts
@@ -0,0 +1,79 @@
+import { CollectionFlagSet } from '~/flagsets'
+import {
+    applyDeclarations,
+    FlagWithValue,
+    FlagWithValueOrOrdinal,
+    ListOfFlagsWithValue,
+    ListOfFlagsWithValueOrOrdinal,
+    NamedFlagWithValue,
+    NamedFlagWithValueOrOrdinal,
+} from './declarative'
+import { FlagDefinition } from '~/definitions'
+import {
+    DefineWithValueOrOrdinal,
+    RequireParentsOrDefineWithValueOrOrdinal,
+    WithValueOrOrdinal,
+    WithValueOrOrdinalOrCompose,
+} from './syntax'
+import { FlagSetBuilder } from './generic'
+import { CollectionFlagDefinitionFactory } from '~/definitions/collection'
+
+export class CollectionFlagSetBuilder<T>
+    implements
+        WithValueOrOrdinalOrCompose<T, Set<T>, CollectionFlagSet<T>>,
+        RequireParentsOrDefineWithValueOrOrdinal<T, Set<T>, CollectionFlagSet<T>>
+{
+    private readonly _underlying: FlagSetBuilder<T>
+
+    public constructor() {
+        this._underlying = new FlagSetBuilder()
+    }
+
+    public define(): WithValueOrOrdinal<T, Set<T>, CollectionFlagSet<T>>
+    public define(alias: string): WithValueOrOrdinalOrCompose<T, Set<T>, CollectionFlagSet<T>>
+    public define(alias?: string): WithValueOrOrdinalOrCompose<T, Set<T>, CollectionFlagSet<T>> {
+        this._underlying.define(alias)
+        return this
+    }
+
+    public compose(...flags: string[]): DefineWithValueOrOrdinal<T, Set<T>, CollectionFlagSet<T>> {
+        this._underlying.compose(flags)
+        return this
+    }
+
+    public withValue(
+        value: T,
+    ): RequireParentsOrDefineWithValueOrOrdinal<T, Set<T>, CollectionFlagSet<T>> {
+        this._underlying.withValue(value)
+        return this
+    }
+
+    public withOrdinal(
+        ordinal: number,
+    ): RequireParentsOrDefineWithValueOrOrdinal<T, Set<T>, CollectionFlagSet<T>> {
+        throw new Error('Method not implemented.')
+    }
+
+    public requires(...flags: string[]): DefineWithValueOrOrdinal<T, Set<T>, CollectionFlagSet<T>> {
+        this._underlying.requires(flags)
+        return this
+    }
+
+    public getResult(): CollectionFlagSet<T> {
+        const graph = this._underlying.finish()
+        const factory = new CollectionFlagDefinitionFactory<T>()
+        return new CollectionFlagSet(graph.intoDictionary(factory))
+    }
+}
+
+export function createCollectionFlagSet<T>(declarations: FlagWithValue<T>[]): CollectionFlagSet<T>
+export function createCollectionFlagSet<T, D extends string>(
+    declarations: Record<D, NamedFlagWithValue<T>>,
+): CollectionFlagSet<T> & Record<D, FlagDefinition<Set<T>>>
+export function createCollectionFlagSet<T>(
+    declarations: ListOfFlagsWithValue<T>,
+): CollectionFlagSet<T> {
+    const builder = new CollectionFlagSetBuilder<T>()
+    applyDeclarations(declarations, builder)
+    return builder.getResult()
+}
diff --git a/node/src/builders/index.ts b/node/src/builders/index.ts
index c4a143d..d56c462 100644
--- a/node/src/builders/index.ts
+++ b/node/src/builders/index.ts
@@ -1 +1,2 @@
 export { BitFlagSetBuilder, createBitFlagSet } from './number'
+export { createCollectionFlagSet, CollectionFlagSetBuilder } from './collection'
diff --git a/node/src/builders/number.ts b/node/src/builders/number.ts
index a1e6049..c313036 100644
--- a/node/src/builders/number.ts
+++ b/node/src/builders/number.ts
@@ -57,7 +57,6 @@ export class BitFlagSetBuilder
 
     public getResult(): BitFlagSet {
         const graph = this._underlying.finish()
-        const definitions = graph.sortedDefinitions()
         const factory = new BitFlagDefinitionFactory()
         return new BitFlagSet(graph.intoDictionary(factory))
     }
@@ -66,7 +65,7 @@ export class BitFlagSetBuilder
 export function createBitFlagSet(declarations: FlagWithValueOrOrdinal<number>[]): BitFlagSet
 export function createBitFlagSet<D extends string>(
     declarations: Record<D, NamedFlagWithValueOrOrdinal<number>>,
-): BitFlagSet & Record<D, FlagDefinition<number, number>>
+): BitFlagSet & Record<D, FlagDefinition<number>>
 export function createBitFlagSet(declarations: ListOfFlagsWithValueOrOrdinal<number>): BitFlagSet {
     const builder = new BitFlagSetBuilder()
     applyDeclarations(declarations, builder)
diff --git a/node/src/definitions/collection.ts b/node/src/definitions/collection.ts
new file mode 100644
index 0000000..3776484
--- /dev/null
+++ b/node/src/definitions/collection.ts
@@ -0,0 +1,104 @@
+import { FlagDefinition, FlagDefinitionFactory, PartialFlagDefinition } from '.'
+import { ENV_SET } from '~/env'
+
+export class CollectionFlagDefinition<T> implements FlagDefinition<Set<T>> {
+    private readonly _value: T | undefined
+    private readonly _alias: string | undefined
+    private readonly _parents: CollectionFlagDefinition<T>[]
+    private readonly _children: CollectionFlagDefinition<T>[]
+
+    public constructor(
+        value: T | undefined,
+        alias: string | undefined,
+        parents: CollectionFlagDefinition<T>[],
+    ) {
+        this._value = value
+        this._alias = alias
+        this._parents = parents
+        this._children = []
+
+        for (const parent of this._parents) {
+            parent._children.push(this)
+        }
+    }
+
+    public get alias(): string | undefined {
+        return this._alias
+    }
+
+    public get values(): Set<T> {
+        let values = new Set<T>()
+        if (this._value === undefined) {
+            for (const parent of this._parents) {
+                values = ENV_SET.union.call(values, parent.values) as Set<T>
+            }
+        } else {
+            values.add(this._value)
+        }
+        return values
+    }
+
+    public isIn(set: Set<T>): boolean {
+        let result = this._value === undefined || set.has(this._value)
+        for (const parent of this._parents) {
+            result &&= parent.isIn(set)
+        }
+        return result
+    }
+
+    public addTo(set: Set<T>): Set<T> {
+        const result = new Set(set)
+        if (this._value !== undefined) {
+            result.add(this._value)
+        }
+        for (const parent of this._parents) {
+            parent.addToMutable(result)
+        }
+        return result
+    }
+
+    private addToMutable(set: Set<T>): void {
+        if (this._value !== undefined) {
+            set.add(this._value)
+        }
+        for (const parent of this._parents) {
+            parent.addToMutable(set)
+        }
+    }
+
+    public removeFrom(set: Set<T>): Set<T> {
+        const result = new Set(set)
+        if (this._value !== undefined) {
+            result.delete(this._value)
+        }
+        for (const parent of this._parents) {
+            parent.removeFromMutable(result)
+        }
+        return result
+    }
+
+    public removeFromMutable(set: Set<T>): void {
+        if (this._value !== undefined) {
+            set.delete(this._value)
+        }
+        for (const child of this._children) {
+            child.removeFromMutable(set)
+        }
+    }
+}
+
+export class CollectionFlagDefinitionFactory<T> implements FlagDefinitionFactory<T, Set<T>> {
+    public makeDefinitions(
+        sortedPartialDefinitions: PartialFlagDefinition<T>[],
+        results: Map<PartialFlagDefinition<T>, FlagDefinition<Set<T>>>,
+    ): void {
+        for (const pfd of sortedPartialDefinitions) {
+            const parents: CollectionFlagDefinition<T>[] = []
+            for (const parentPfd of pfd.parents) {
+                parents.push(results.get(parentPfd) as CollectionFlagDefinition<T>)
+            }
+
+            results.set(pfd, new CollectionFlagDefinition(pfd.value, pfd.alias, parents))
+        }
+    }
+}
diff --git a/node/src/definitions/dictionary.ts b/node/src/definitions/dictionary.ts
index d6c3834..3250d7f 100644
--- a/node/src/definitions/dictionary.ts
+++ b/node/src/definitions/dictionary.ts
@@ -1,10 +1,10 @@
 export interface FlagsDictionary<F, S> {
-    findByAlias(alias: string): FlagDefinition<F, S> | undefined
+    findByAlias(alias: string): FlagDefinition<S> | undefined
 
-    findByValue(value: F): FlagDefinition<F, S> | undefined
+    findByValue(value: F): FlagDefinition<S> | undefined
 }
 
-export interface FlagDefinition<F, S> {
+export interface FlagDefinition<S> {
     /**
      * The alias of the flag.
      */
@@ -39,9 +39,9 @@ export interface FlagDefinition<F, S> {
 
 export const valueToString = Symbol()
 
-export function printFlagValue(flag: FlagDefinition<unknown, unknown>): string {
+export function printFlagValue(flag: FlagDefinition<unknown>): string {
     if (valueToString in flag) {
-        return (flag[valueToString] as Function)()
+        return (flag[valueToString] as () => string)()
     } else {
         return String(flag.values)
     }
diff --git a/node/src/definitions/number.ts b/node/src/definitions/number.ts
index bdbe98e..136929c 100644
--- a/node/src/definitions/number.ts
+++ b/node/src/definitions/number.ts
@@ -6,7 +6,7 @@ interface PrecomputedValues {
     subtractive: number
 }
 
-export class BitFlagDefinition implements FlagDefinition<number, number> {
+export class BitFlagDefinition implements FlagDefinition<number> {
     private readonly _baseValue: number
     private readonly _additiveValue: number
     private readonly _subtractiveValue: number
@@ -43,7 +43,7 @@ export class BitFlagDefinition implements FlagDefinition<number, number> {
 export class BitFlagDefinitionFactory implements FlagDefinitionFactory<number, number> {
     public makeDefinitions(
         sortedPartialDefinitions: PartialFlagDefinition<number>[],
-        results: Map<PartialFlagDefinition<number>, FlagDefinition<number, number>>,
+        results: Map<PartialFlagDefinition<number>, FlagDefinition<number>>,
     ): void {
         const precomputedValues = new Map<PartialFlagDefinition<number>, PrecomputedValues>()
 
diff --git a/node/src/env.ts b/node/src/env.ts
index d1455d6..18bf332 100644
--- a/node/src/env.ts
+++ b/node/src/env.ts
@@ -11,18 +11,12 @@ export const ENV_BI = Object.freeze(
 type SetBinaryOperation = <T>(this: Set<T>, other: Set<T>) => Set<T>
 type SetBinaryPredicate = <T>(this: Set<T>, other: Set<T>) => boolean
 
-export const ENV_SET = Object.freeze(
-    typeof Set === 'function'
-        ? {
-              AVAILABLE: true,
-              union: polyfillUnion(Set.prototype),
-              intersection: polyfillIntersection(Set.prototype),
-              difference: polyfillDifference(Set.prototype),
-              isSupersetOf: polyfillIsSupersetOf(Set.prototype),
-          }
-        : { AVAILABLE: false },
-) as {
-    readonly AVAILABLE: boolean
+export const ENV_SET = Object.freeze({
+    union: polyfillUnion(Set.prototype),
+    intersection: polyfillIntersection(Set.prototype),
+    difference: polyfillDifference(Set.prototype),
+    isSupersetOf: polyfillIsSupersetOf(Set.prototype),
+}) as {
     readonly union: SetBinaryOperation
     readonly intersection: SetBinaryOperation
     readonly difference: SetBinaryOperation
diff --git a/node/src/flagsets/collection.ts b/node/src/flagsets/collection.ts
index 1199dcb..b73879b 100644
--- a/node/src/flagsets/collection.ts
+++ b/node/src/flagsets/collection.ts
@@ -1,23 +1,35 @@
+import { FlagDefinition, FlagsDictionary } from '~/definitions'
+import { EnumerateFlags } from '~/enumeration'
+import { ENV_SET } from '~/env'
+
 import type { FlagSet } from '.'
-import { EnumerateFlags, useIterator } from '../enumeration'
-import { ENV_SET } from '../env'
-import { UnavailableFeatureError } from '../errors'
 
 export class CollectionFlagSet<T> implements FlagSet<T, Set<T>> {
-    /**
-     * Creates a new empty flag set.
-     *
-     * @throws UnavailableFeatureError When this constructor is called in an
-     *         environment that does not natively support {@link Set}s.
-     */
-    public constructor() {
-        if (!ENV_SET.AVAILABLE) {
-            throw new UnavailableFeatureError('Sets')
-        }
+    private readonly _dictionary: FlagsDictionary<T, Set<T>>
+
+    public constructor(dictionary: FlagsDictionary<T, Set<T>>) {
+        this._dictionary = dictionary
     }
 
     public none(): Set<T> {
-        return new Set()
+        return new Set<T>()
+    }
+
+    public of(...values: T[]): Set<T> {
+        return new Set(values)
+    }
+
+    public named(...aliases: string[]): Set<T> {
+        const result = new Set<T>()
+        for (const alias of aliases) {
+            const definition = this.getFlag(alias)
+            if (definition !== undefined) {
+                for (const value of definition.values) {
+                    result.add(value)
+                }
+            }
+        }
+        return result
     }
 
     public union(first: Set<T>, second: Set<T>): Set<T> {
@@ -36,18 +48,57 @@ export class CollectionFlagSet<T> implements FlagSet<T, Set<T>> {
         return ENV_SET.isSupersetOf.call(first, second)
     }
 
+    public hasAny(flags: Set<T>, required: Set<T>): boolean {
+        let result = false
+        for (const value of required) {
+            const definition = this._dictionary.findByValue(value)
+            if (definition !== undefined && definition.isIn(flags)) {
+                result = true
+                break
+            }
+        }
+        return result
+    }
+
+    public hasAll(flags: Set<T>, required: Set<T>): boolean {
+        let result = true
+        for (const value of required) {
+            const definition = this._dictionary.findByValue(value)
+            if (definition !== undefined && !definition.isIn(flags)) {
+                result = false
+                break
+            }
+        }
+        return result
+    }
+
     public enumerate(flags: Set<T>): EnumerateFlags<T> {
         return flags
     }
 
-    minimum(flags: Set<T>): Set<T> {
-        throw new Error('Method not implemented.')
-    }
-    maximum(flags: Set<T>): Set<T> {
-        throw new Error('Method not implemented.')
+    public maximum(flags: Set<T>): Set<T> {
+        let result = new Set<T>()
+        for (const value of flags) {
+            const definition = this._dictionary.findByValue(value)
+            if (definition !== undefined) {
+                result = definition.addTo(result)
+            }
+        }
+        return result
     }
 
-    public getFlag(alias: string): FlagDefinition<number, number> | undefined {
-        return this._dictionary.lookUp(alias)
+    public minimum(flags: Set<T>): Set<T> {
+        let result = new Set<T>()
+        for (const value of flags) {
+            const definition = this._dictionary.findByValue(value)
+            if (definition !== undefined && definition.isIn(flags)) {
+                result = definition.addTo(result)
+            }
+        }
+        return result
+    }
+
+    public getFlag(alias: string): FlagDefinition<Set<T>> | undefined {
+        return this._dictionary.findByAlias(alias)
     }
 }
diff --git a/node/src/flagsets/number.ts b/node/src/flagsets/number.ts
index 0172f13..c8e4e77 100644
--- a/node/src/flagsets/number.ts
+++ b/node/src/flagsets/number.ts
@@ -91,28 +91,28 @@ export class BitFlagSet implements FlagSet<number, number> {
     }
 
     public maximum(flags: number): number {
-        let result = this.none()
+        let result = 0
         for (const value of this.enumerate(flags)) {
-            const flag = this._dictionary.findByValue(value)
-            if (flag !== undefined) {
-                result = flag.addTo(result)
+            const definition = this._dictionary.findByValue(value)
+            if (definition !== undefined) {
+                result = definition.addTo(result)
             }
         }
         return result
     }
 
     public minimum(flags: number): number {
-        let result = this.none()
+        let result = 0
         for (const value of this.enumerate(flags)) {
-            const flag = this._dictionary.findByValue(value)
-            if (flag !== undefined && flag.isIn(flags)) {
-                result = flag.addTo(result)
+            const definition = this._dictionary.findByValue(value)
+            if (definition !== undefined && definition.isIn(flags)) {
+                result = definition.addTo(result)
             }
         }
         return result
     }
 
-    public getFlag(alias: string): FlagDefinition<number, number> | undefined {
+    public getFlag(alias: string): FlagDefinition<number> | undefined {
         return this._dictionary.findByAlias(alias)
     }
 }
diff --git a/node/src/index.ts b/node/src/index.ts
index ed16209..8fdb435 100644
--- a/node/src/index.ts
+++ b/node/src/index.ts
@@ -1,4 +1,4 @@
-export { createBitFlagSet } from './builders'
+export { createBitFlagSet, createCollectionFlagSet } from './builders'
 export { FlagDefinition } from './definitions'
 export { InvalidBitFlagValueError } from './errors'
 export {
diff --git a/node/tests/flagsets/collection.test.ts b/node/tests/flagsets/collection.test.ts
index e2964a9..6359ab5 100644
--- a/node/tests/flagsets/collection.test.ts
+++ b/node/tests/flagsets/collection.test.ts
@@ -1,19 +1,41 @@
-import { CollectionFlagSet } from '~'
 import { describe, expect, test } from 'vitest'
 
+import { CollectionFlagSet, createCollectionFlagSet } from '~'
+
 function set<T>(...values: T[]): Set<T> {
     return new Set<T>(values)
 }
 
 describe(CollectionFlagSet, () => {
     test('none', () => {
-        const flags = new CollectionFlagSet<string>()
+        const flags = createCollectionFlagSet<string>([])
 
         expect(flags.none()).toEqual(set())
     })
 
+    test('of', () => {
+        const flags = createCollectionFlagSet<string>([])
+
+        expect(flags.of()).toEqual(set())
+        expect(flags.of('a')).toEqual(set('a'))
+        expect(flags.of('x', 'y', 'z')).toEqual(set('x', 'y', 'z'))
+    })
+
+    test('named', () => {
+        const flags = createCollectionFlagSet([
+            { value: 12, as: 'a' },
+            { value: 45, as: 'b' },
+            { value: 78, as: 'c' },
+            { compose: ['a', 'b'], as: 'ab' },
+        ])
+
+        expect(flags.named()).toEqual(set())
+        expect(flags.named('a')).toEqual(set(12))
+        expect(flags.named('ab', 'c')).toEqual(set(12, 45, 78))
+    })
+
     test('union', () => {
-        const flags = new CollectionFlagSet<string>()
+        const flags = createCollectionFlagSet<string>([])
 
         expect(flags.union(set(), set())).toEqual(set())
         expect(flags.union(set('A'), set())).toEqual(set('A'))
@@ -23,7 +45,7 @@ describe(CollectionFlagSet, () => {
     })
 
     test('difference', () => {
-        const flags = new CollectionFlagSet<string>()
+        const flags = createCollectionFlagSet<string>([])
 
         expect(flags.difference(set(), set())).toEqual(set())
         expect(flags.difference(set('A'), set())).toEqual(set('A'))
@@ -33,7 +55,7 @@ describe(CollectionFlagSet, () => {
     })
 
     test('intersection', () => {
-        const flags = new CollectionFlagSet<string>()
+        const flags = createCollectionFlagSet<string>([])
 
         expect(flags.intersection(set(), set())).toEqual(set())
         expect(flags.intersection(set('A'), set())).toEqual(set())
@@ -44,7 +66,7 @@ describe(CollectionFlagSet, () => {
     })
 
     test('isSuperset', () => {
-        const flags = new CollectionFlagSet<string>()
+        const flags = createCollectionFlagSet<string>([])
 
         expect(flags.isSuperset(set(), set())).toBe(true)
         expect(flags.isSuperset(set('A', 'B'), set())).toBe(true)
@@ -55,7 +77,7 @@ describe(CollectionFlagSet, () => {
     })
 
     test('enumerate', () => {
-        const flags = new CollectionFlagSet<string>()
+        const flags = createCollectionFlagSet<string>([])
 
         expect([...flags.enumerate(set())]).toEqual([])
         expect([...flags.enumerate(set('A'))]).toEqual(['A'])
diff --git a/node/tests/flagsets/number.test.ts b/node/tests/flagsets/number.test.ts
index 2490eb4..156f780 100644
--- a/node/tests/flagsets/number.test.ts
+++ b/node/tests/flagsets/number.test.ts
@@ -34,37 +34,45 @@ describe(BitFlagSet, () => {
     })
 
     test('union', () => {
-        expect(BitFlags.union(0, 0)).toEqual(0)
-        expect(BitFlags.union(1, 0)).toEqual(1)
-        expect(BitFlags.union(0, 2)).toEqual(2)
-        expect(BitFlags.union(1, 2)).toEqual(3)
-        expect(BitFlags.union(3, 6)).toEqual(7)
+        const flags = createBitFlagSet([])
+
+        expect(flags.union(0, 0)).toEqual(0)
+        expect(flags.union(1, 0)).toEqual(1)
+        expect(flags.union(0, 2)).toEqual(2)
+        expect(flags.union(1, 2)).toEqual(3)
+        expect(flags.union(3, 6)).toEqual(7)
     })
 
     test('difference', () => {
-        expect(BitFlags.difference(0, 0)).toEqual(0)
-        expect(BitFlags.difference(1, 0)).toEqual(1)
-        expect(BitFlags.difference(3, 6)).toEqual(1)
-        expect(BitFlags.difference(6, 3)).toEqual(4)
-        expect(BitFlags.difference(8, 17)).toEqual(8)
+        const flags = createBitFlagSet([])
+
+        expect(flags.difference(0, 0)).toEqual(0)
+        expect(flags.difference(1, 0)).toEqual(1)
+        expect(flags.difference(3, 6)).toEqual(1)
+        expect(flags.difference(6, 3)).toEqual(4)
+        expect(flags.difference(8, 17)).toEqual(8)
     })
 
     test('intersection', () => {
-        expect(BitFlags.intersection(0, 0)).toEqual(0)
-        expect(BitFlags.intersection(1, 0)).toEqual(0)
-        expect(BitFlags.intersection(1, 2)).toEqual(0)
-        expect(BitFlags.intersection(1, 3)).toEqual(1)
-        expect(BitFlags.intersection(11, 5)).toEqual(1)
-        expect(BitFlags.intersection(11, 7)).toEqual(3)
+        const flags = createBitFlagSet([])
+
+        expect(flags.intersection(0, 0)).toEqual(0)
+        expect(flags.intersection(1, 0)).toEqual(0)
+        expect(flags.intersection(1, 2)).toEqual(0)
+        expect(flags.intersection(1, 3)).toEqual(1)
+        expect(flags.intersection(11, 5)).toEqual(1)
+        expect(flags.intersection(11, 7)).toEqual(3)
     })
 
     test('isSuperset', () => {
-        expect(BitFlags.isSuperset(0, 0)).toBe(true)
-        expect(BitFlags.isSuperset(3, 0)).toBe(true)
-        expect(BitFlags.isSuperset(3, 1)).toBe(true)
-        expect(BitFlags.isSuperset(3, 3)).toBe(true)
-        expect(BitFlags.isSuperset(0, 3)).toBe(false)
-        expect(BitFlags.isSuperset(8, 4)).toBe(false)
+        const flags = createBitFlagSet([])
+
+        expect(flags.isSuperset(0, 0)).toBe(true)
+        expect(flags.isSuperset(3, 0)).toBe(true)
+        expect(flags.isSuperset(3, 1)).toBe(true)
+        expect(flags.isSuperset(3, 3)).toBe(true)
+        expect(flags.isSuperset(0, 3)).toBe(false)
+        expect(flags.isSuperset(8, 4)).toBe(false)
     })
 
     test('hasAny', () => {
@@ -100,12 +108,14 @@ describe(BitFlagSet, () => {
     })
 
     test('enumerate', () => {
-        expect([...BitFlags.enumerate(0)]).toEqual([])
-        expect([...BitFlags.enumerate(1)]).toEqual([1])
-        expect([...BitFlags.enumerate(2)]).toEqual([2])
-        expect([...BitFlags.enumerate(3)]).toEqual([1, 2])
-        expect([...BitFlags.enumerate(11)]).toEqual([1, 2, 8])
-        expect([...BitFlags.enumerate(100)]).toEqual([4, 32, 64])
+        const flags = createBitFlagSet([])
+
+        expect([...flags.enumerate(0)]).toEqual([])
+        expect([...flags.enumerate(1)]).toEqual([1])
+        expect([...flags.enumerate(2)]).toEqual([2])
+        expect([...flags.enumerate(3)]).toEqual([1, 2])
+        expect([...flags.enumerate(11)]).toEqual([1, 2, 8])
+        expect([...flags.enumerate(100)]).toEqual([4, 32, 64])
     })
 
     test('maximum', () => {
@@ -140,3 +150,48 @@ describe(BitFlagSet, () => {
         expect(flags.minimum(13)).toEqual(5)
     })
 })
+
+describe('BitFlags', () => {
+    test('union', () => {
+        expect(BitFlags.union(0, 0)).toEqual(0)
+        expect(BitFlags.union(1, 0)).toEqual(1)
+        expect(BitFlags.union(0, 2)).toEqual(2)
+        expect(BitFlags.union(1, 2)).toEqual(3)
+        expect(BitFlags.union(3, 6)).toEqual(7)
+    })
+
+    test('difference', () => {
+        expect(BitFlags.difference(0, 0)).toEqual(0)
+        expect(BitFlags.difference(1, 0)).toEqual(1)
+        expect(BitFlags.difference(3, 6)).toEqual(1)
+        expect(BitFlags.difference(6, 3)).toEqual(4)
+        expect(BitFlags.difference(8, 17)).toEqual(8)
+    })
+
+    test('intersection', () => {
+        expect(BitFlags.intersection(0, 0)).toEqual(0)
+        expect(BitFlags.intersection(1, 0)).toEqual(0)
+        expect(BitFlags.intersection(1, 2)).toEqual(0)
+        expect(BitFlags.intersection(1, 3)).toEqual(1)
+        expect(BitFlags.intersection(11, 5)).toEqual(1)
+        expect(BitFlags.intersection(11, 7)).toEqual(3)
+    })
+
+    test('isSuperset', () => {
+        expect(BitFlags.isSuperset(0, 0)).toBe(true)
+        expect(BitFlags.isSuperset(3, 0)).toBe(true)
+        expect(BitFlags.isSuperset(3, 1)).toBe(true)
+        expect(BitFlags.isSuperset(3, 3)).toBe(true)
+        expect(BitFlags.isSuperset(0, 3)).toBe(false)
+        expect(BitFlags.isSuperset(8, 4)).toBe(false)
+    })
+
+    test('enumerate', () => {
+        expect([...BitFlags.enumerate(0)]).toEqual([])
+        expect([...BitFlags.enumerate(1)]).toEqual([1])
+        expect([...BitFlags.enumerate(2)]).toEqual([2])
+        expect([...BitFlags.enumerate(3)]).toEqual([1, 2])
+        expect([...BitFlags.enumerate(11)]).toEqual([1, 2, 8])
+        expect([...BitFlags.enumerate(100)]).toEqual([4, 32, 64])
+    })
+})