Provides identity
Identity principle
Allowed supertypes
Category, Mixin
Allowed subtypes
Subkind, Phase, Role
Forbidden associations
ComponentOf, Derivation, Structuration, SubCollectionOf


The «Quantity» construct is used to represent rigid concepts that provide an identity principle for their instances. A «Quantity» represent uncountable things, like Water, Clay, or Beer. It represents a maximally topologically connected amount of matter. Quantities only have other quantities as parts (see the «SubQuantityOf» relation for more details about members of collections). Here are some examples:

Quantity examples

An easy way to decide whether a concept is a quantity or not, as yourself this: if you physically divide an instance of ‘x’ in two parts, are the resulting individuals two new instances of x? What if you divide another 5 or 10 times? If the answer is always yes, ‘x’ is a Quantity. To exemplify, let’s think about an pile of sand. If you divide the pile in two, you now have to new piles of sand, right? What if you do that again for each remaining part? We would have 4 piles of sand.

Tannin heap

As the other identity provider stereotypes («Kind», «Collective», «Relator» and «Mode»), a Quality can be specialized by subkinds, phases and roles, as well as generalized by mixins and categories.

Quantity application 1

Be careful not to confuse «Quantity» and «Quality».


C1: A «Quantity» cannot have an identity providerKind», «Collective», «Quantity», «Relator», «Mode» and «Quantity») as its direct or indirect super-type.

Quantity forbidden 1

C2: A «Quantity» cannot have types that inherit identitySubkind», «Role» and «Phase») as its direct or indirect super-types.

Quantity forbidden 2

C3: A «Quantity» cannot have types that aggregate individuals with different identity principlesCategory», «RoleMixin» and «Mixin») as its direct or indirect subtypes.

Quantity forbidden 3

C4: As a rigid type, a «Quantity» cannot have any anti-rigid type («Role», «RoleMixin» and «Phase») as its direct or indirect super-type.

Quantity forbidden 4

Common questions

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