NIIMBL Physical Model Ontology
type: Ontology
label: Physical Model Ontology
abstract: This module contains terms and relations to represent the physical spaces where processing and storage occurs. Spaces are specific and bounded geographic locations which can be heirarchical and embedded.
contributor: Adlane Rebai, Millipore Sigma
contributor: Ana Nikolov, OAGi
contributor: Boonserm Kulvatunyou, NIST
contributor: Cameron Gibbs, CrownPoint Technologies, LLC
contributor: Gabriela Henning, NIST
contributor: Jan Kemper, AstraZeneca
contributor: Marie-Aude Coutouly, Millipore Sigma
contributor: Melissa Weller, CrownPoint Technologies, LLC
contributor: Milos Drobnjakovic, OAGi
contributor: Stephen J. Granite, CrownPoint Technologies, LLC
contributor: Stephen Kahmann, CrownPoint Technologies, LLC
creator: NIIMBL BD-1 Ontology Group
license: http://opensource.org/licenses/MIT
imports: Core
version IRI: ManufacturingSystemOrganization
copyright: Copyright (c) 2022, 2023, 2024, 2025, 2026 Open Applications Group
maturity: Released

control module
type: Class
subclass of: BFO_0000027
example: a control valve module that manages the operation of a single control valve, including opening, closing, and positioning the valve based on a given setpoint or control signal; a motor starter module, which is responsible for starting, stopping, and monitoring the status of the motor of a pump or an agitator, and includes the logic for interlocks, overload protection, and feedback signals; a level control module that monitors the level inside a tank and provides an alarm or initiates control actions when a certain level is reached
adapted from: ISA88
explanatory note: A control module can consider a person as its member. For example, a human operator can open and close valves.
first order logic axiom: ControlModule(x) → ObjectAggregate(x)
is primitive: true
natural language definition: object aggregate that is a lowest level grouping that can carry out basic control
primitive rationale: There are currently insufficient constructs to adequately model carrying out basic control.
semi formal natural language axiom: if x is a 'control module' then x is an 'object aggregate'

enterprise
type: Class
subclass of: BusinessOrganization
example: oil and gas company that explores, extracts, refines, and distributes petroleum products; aerospace alliance that produces aircraft components, assembles them into final products and provides services to these aircrafts; multinational automotive manufacturer; pharmaceutical company that develops, manufactures, and supplies prescription medicines, vaccines, and animal health products
adapted from: ISA95 and ISA88
explanatory note: ISA-95 and ISA-88 business organization that coordinates the operation of one or more physical sites or areas
first order logic axiom: Enterprise(x) → BusinessOrganization(x)
is primitive: true
natural language definition: business organization that is at the highest decision-making and control to achieve the common mission, goals, and objectives of manufacturing or providing products or services by coordinating one or more physical sites
primitive rationale: There are insufficient constructs to fully define enterprise at this moment.
semi formal natural language axiom: if x is an 'enterprise' then x is a 'business organization'

equipment module
type: Class
subclass of: EngineeredSystem
subclass of: Restriction
  on property: BFO_0000172
  some values from: PieceOfEquipment
example: a heating or cooling system of a reactor or bioreactor that includes the reactor’s jacket, temperature sensors, control valves, and the control logic needed to regulate the heating or cooling process; an agitator system in a mixing tank, which consists of the agitator, its motor, the speed controller, associated sensors, and the control logic that manages starting, stopping, and speed adjustment; a liquids dosing system of a mixer, blender, or reactor that includes pumps, flowmeters, valves, and control logic to ensure accurate dosing; a solids dosing system of a mixer, blender, or reactor that includes feeders, a weigh tank, valves, and control logic to ensure accurate dosing; a CIP (Clean-In-Place) skid that automates the cleaning of equipment and piping in a process cell, including tanks for fluids, pumps, valves, sensors, and control logic to sequence cleaning steps; and a venting system of a reactor or vessel that includes pressure sensors, vent valves, and the logic to safely evacuate the unit as needed
adapted from: ISA88 Part 1
explanatory note: ISA88: functional group of equipment that can carry out a number of specific minor processing activities
first order logic axiom: LA1: EquipmentModule(x) → EngineeredSystem(x) ∧ ∃y(PieceOfEquipment(y) ∧ hasMemberPartAtAllTimes(x, y))
first order logic axiom: LA2: EngineeredSystem(x) ∧ ∃a (isCarrierOfAtSomeTime(x, a) ∧ RecipePhase(a)) ∧ ∃b (memberPartOfAtSomeTime(x, b) ∧ PhysicalUnit(b)) ∧ ∃c (hasMemberPartAtAllTimes(x, c) ∧ PieceOfEquipment(c)) → EquipmentModule(x)
is primitive: true
natural language definition: enginereed system typically centered around a piece of equipment that carries out some phase
primitive rationale: This term is expected to remain primitive, as identifying a set of necessary conditions that consistently hold and align with the given sufficient condition is challenging.
semi formal natural language axiom: LA1: if x is an 'equipment module' then x is an 'engineered system' that 'has member part at all times' some 'piece of equipment'
semi formal natural language axiom: LA2: if x is an 'engineered system' that 'is carrier of at some time' some 'recipe phase', 'is member part of at some time' some 'physical unit', and 'has member part at all times' some 'piece of equipment', then x is an 'equipment module'
usage note: The OWL formalization of LA2 relies on classes defined within the recipe module. Accordingly, the sufficient condition for LA2 is implemented in OWL as part of the recipe module, rather than within the physical module.

physical area
type: Class
subclass of: BFO_0000027
subclass of: Restriction
  on property: BFO_0000115
  all values from: Class
    union of: work center
    union of: work unit
subclass of: Restriction
  on property: BFO_0000173
  some values from: physical site
example: dock area of an oil terminal; fuselage assembly area of an aircraft factory; ground testing area of a facility that performs maintenance, repair, and overhaul services on an aircraft line; liquid effluent treatment plant that is part of an antibiotic manufacturing facility; utilities area of an oral liquids manufacturing plant
adapted from: ISA95 and ISA88 Part 1
explanatory note: The boundaries (scope) of the site is typically determined by business/organizational criteria and not technical criteria Within the manufacturing domain, area typically serves as a way to organize manufacturing operations (ISA95 operation) within a site
first order logic axiom: PhysicalArea(x) → ObjectAggregate(x) ∧ ∀y(hasMemberPartAtSomeTime(x,y) → (WorkCenter(y) ∨ WorkUnit(y))) ∧ ∃z(PhysicalSite(z) ∧ memberPartOfAtAllTimes(x,z))
is primitive: true
natural language definition: object aggregate that is a physical, geographical, or logical grouping of one or more work centers or work units within a physical site
primitive rationale: This term is expected to remain primitive as the exact grouping criteria are ogranization specific
semi formal natural language axiom: if x is a 'physical area', then x is an 'object aggregate', every entity that x 'has member part at some time' is a 'work center' or 'work unit', and x is 'member part of at all times' some 'physical site'

physical site
type: Class
subclass of: BFO_0000027
subclass of: Restriction
  on property: BFO_0000115
  all values from: Class
    union of: physical area
    union of: work center
    union of: work unit
subclass of: Restriction
  on property: prescribedBy
  some values from: Class
    intersection of: InformationContentEntity
    intersection of: Restriction
      on property: BFO_0000084
      some values from: enterprise
example: refinery located in Houston, TX, which belongs to an oil and gas company; oil terminal located at the coast of Houston, TX, which belongs to an oil and gas company; factory that produces an aircraft line and belongs to an aerospace alliance; facility that performs maintenance, repair, and overhaul services on an aircraft line and belongs to an aerospace alliance; antibiotic production facility that belongs to a pharmaceutical company; oral liquids manufacturing plant that belongs to a pharmaceutical company; factory that produces SUV cars and belongs to a multinational automotive manufacturer; proving ground facility where a multinational automotive manufacturer tests its vehicles
adapted from: ISA95 and ISA88 part 1
explanatory note: A geographical location and the main manufacturing capability typically define a physical site A site usually has a manufacturing capability associated to a particular family of products The boundaries (scope) of the site is typically determined by business/organizational criteria and not technical criteria
first order logic axiom: PhysicalSite(x) → ObjectAggregate(x) ∧ ∀y(hasMemberPartAtSomeTime(x, y) → (PhysicalArea(y) ∨ WorkCenter(y) ∨ WorkUnit(y))) ∧ ∃i,e(InformationContentEntity(i) ∧ prescribedBy(x, i) ∧ Enterprise(e) ∧ genericallyDependsOnAtSomeTime(i, e))
is primitive: true
natural language definition: object aggregate that is a physical, geographical, or logical grouping of physical areas, work centers or work units determined by the enterprise
primitive rationale: This term is expected to remain primitive as the exact grouping criteria are ogranization specific
semi formal natural language axiom: if x is a 'physical site' then x is an 'object aggregate' that 'has member part at some time' only a 'physical area', 'work center', or 'work unit', and is 'prescribed by' some 'information content entity' that 'generically depends on at some time' some 'enterprise'

physical unit
type: Class
subclass of: work unit
subclass of: Restriction
  on property: BFO_0000115
  all values from: Class
    complement of: physical unit
example: a vessel that can carry out a fermentation; a ribbon blender, double cone blender, or V blender that can perform a variety of blending or mixing operations; an evaporative crystallizer or cooling crystallizer; a spray dryer or tray dryer; a shell and tube heat exchanger; a distillation tower; a fixed-bed catalytic reactor; and a flash unit
adapted from: ISA 88 Part 1
explanatory note: ISA-88: collection of associated equipment modules and/or control modules that can carry out one or more major processing activities In rare cases, a unit can carry out an entire procedure. Since a procedure is associated with process cell, this should be modeled as a process cell having a single unit as its member part and then carrying a procedure.
first order logic axiom: LA1:PhysicalUnit(x) → WorkUnit(x) ∧ ¬∃y(PhysicalUnit(y) ∧ hasMemberPartAtSomeTime(x, y))
first order logic axiom: LA2: WorkUnit(x) ∧ ∃y (isCarrierOfAtSomeTime(x, y) ∧ (RecipeOperation(y) ∨ RecipeUnitProcedure(y))) → PhysicalUnit(x)
is primitive: true
natural language definition: work unit that carries out an operation or unit procedure
primitive rationale: This term is expected to remain primitive, as identifying a set of necessary conditions that consistently hold and align with the given sufficient condition is challenging.
semi formal natural language axiom: LA1: if x is a 'physical unit', then x is a 'work unit' and x does not have as a 'member part at some time' any other 'physical unit'
semi formal natural language axiom: LA2: if x is a 'work unit' that 'is carrier of at some time' some 'recipe operation' or 'recipe unit procedure', then x is a 'physical unit'

process cell
type: Class
subclass of: work center
subclass of: Restriction
  on property: BFO_0000172
  some values from: physical unit
example: equipment involved in the production of chocolate paste, including mixers, calendaring and conching equipment, as well as dosing and weighing systems and control equipment; a polyvinyl chloride (PVC) batch production process cell containing several batch reactors, venting and steam stripping units, and spray dryers; a medicine pills production cell including blending units with feeders, granulation units, drying units, grinders, tableting presses, and coaters
adapted from: ISA 88 part 1
explanatory note: ISA88: logical grouping of equipment that includes the equipment required for production of one or more batches
first order logic axiom: LA1:ProcessCell(x) → WorkCenter(x) ∧ ∃y(PhysicalUnit(y) ∧ hasMemberPartAtAllTimes(x, y))
first order logic axiom: LA2: WorkCenter(x) ∧ ∃y (isCarrierOfAtSomeTime(x, y) ∧ ControlRecipe(y)) → ProcessCell(x)
is primitive: true
natural language definition: work center that is required for carrying out some control recipe
primitive rationale: This term is expected to remain primitive, as identifying a set of necessary conditions that consistently hold and align with the given sufficient condition is challenging.
semi formal natural language axiom: LA1:if x is a 'process cell' then x is a 'work center' that 'has member part at all times' some 'physical unit'
semi formal natural language axiom: LA2: if x is a 'work center' that 'is carrier of at some time' some 'control recipe', then x is a 'process cell'
usage note: The OWL formalization of LA2 relies on classes defined within the recipe module. Accordingly, the sufficient condition for LA2 is implemented in OWL as part of the recipe module, rather than within the physical module.

production line
type: Class
subclass of: work center
example: an automotive assembly line having a series of workstations or work cells where car bodies move along a conveyor, and at each station, specific components—such as engines, doors, or seats—are installed by workers and/or robots; a smartphone model production line that includes stations or work cells for mounting circuit boards, installing screens, assembling casings, and performing quality checks; a washing machine production line where the chassis is assembled, components like motors, drums, pipes, and electronic circuits are installed, and the final product is tested and packaged; a candy production line composed of an oven or cooker, forming machines, a cooling tunnel, wrapping machines, and packaging machines
adapted from: ISA 95 and oxford dictionary
first order logic axiom: ProductionLine(x) → WorkCenter(x)
is primitive: true
natural language definition: work center dedicated to the manufacture of a specific product or product family in which the member work units are organized in a sequential manner
primitive rationale: There are insufficient construct to represent the sequential organization of the members that are parts of the production line
semi formal natural language axiom: if x is a 'production line' then x is a 'work center'

production unit
type: Class
subclass of: work center
example: a hydrochloric acid production unit, consisting of a combustion chamber where hydrogen and chlorine react, a cooling system to condense the HCl gas, and an absorption tower where the gas is dissolved in water to form hydrochloric acid; a styrene production unit via catalytic dehydrogenation of ethylbenzene, which includes preheating units, a catalytic reactor, and a separation train comprising a liquid-vapor separator and two distillation towers; a toluene hydrodealkylation production unit that converts toluene into benzene and methane by reacting it with hydrogen in the presence of a catalyst at high temperatures, comprising a furnace, chemical reactor, flash unit, separation columns, compressor, and multiple heat exchangers
adapted from: ISA 95 and https://www.sciencedirect.com/topics/computer-science/production-unit
first order logic axiom: ProductionUnit(x) → WorkCenter(x)
is primitive: true
natural language definition: work center within a broader production system that has specific tasks allocated to it
primitive rationale: There are insufficient constructs to represent task allocation at this point.
semi formal natural language axiom: if x is a 'production unit' then x is a 'work center'

storage unit
type: Class
subclass of: work unit
equivalent class: Class
  intersection of: work unit
  intersection of: Restriction
    on property: BFO_0000173
    some values from: storage zone
example: a tank in a tank farm; a silo in a silo farm; a storage bay or rack in a warehouse or depot; a designated surface in a holding area intended for the storage of a particular product or family of products, such as logs within a certain diameter range and conicity
adapted from: ISA95
explanatory note: ISA 95: work unit that is part of a storage zone that is designated physical space and/or equipment Work unit that is a subdivision of a storage zone
first order logic definition: StorageUnit(x) ↔ WorkUnit(x) ∧ ∃y(StorageZone(y) ∧ memberPartOfAtAllTimes(x, y))
natural language definition: work unit that is a member part of a storage zone
semi formal natural language definition: every instance of a 'storage unit' is defined as exactly an instance of 'work unit' that is the 'member part of at all times' some 'storage zone'

storage zone
type: Class
subclass of: work center
example: a tank farm dedicated to gasoline storage; a silo farm devoted to the storage of different grains; a warehouse or depot intended for the storage of a family of products; a holding area in an open space intended for the storage of bulk products, such as iron ore, coal, or logs
adapted from: ISA95
explanatory note: The capability of the storage zone may include the movement of materials from one work center to another work center within or between enterprises. The ISA-95 specifies that storage zone can either be a designated physical space or equipment for storage of equipment or material. Within the IOF/BFO framework a physical space would be fiat object part, while the equipment is represented by the same IOF Concept - piece of equipment.
first order logic axiom: StorageZone(x) → WorkCenter(x)
is primitive: true
natural language definition: work center dedicated to the storage of materials or equipment
primitive rationale: A clear modeling pattern is needed to define the specific meaning of the term 'dedicated to'. Its formalization will likely require leveraging the concept of 'storage process' from the Supply Chain Ontology.
semi formal natural language axiom: if x is a 'storage zone' then x is a 'work center'

work cell
type: Class
subclass of: work unit
subclass of: Restriction
  on property: BFO_0000129
  some values from: production line
example: an automotive assembly line with a series of workstations or work cells where car bodies move along a conveyor, and at each station, specific components—such as engines, doors, or seats—are installed by workers and/or robots; a smartphone production line that includes stations or work cells for mounting circuit boards, installing screens, assembling casings, and performing quality checks; a washing machine production line having a series of workstations or work cells where the chassis is assembled, components such as motors, drums, pipes, and electronic circuits are installed, and the final product is tested and packaged; a candy production line composed of an oven or cooker, a work cell of forming machines, a cooling tunnel, as well as work cells of wrapping machines, and packaging machines
adapted from: ISA95
explanatory note: 1) ISA95: work unit within a production line that consists of equipment grouped together to produce a family of parts having similar manufacturing requirements. 2) While production lines can be used in discrete or continous manufacturing - work cells are only considered as parts of production lines that are used for discrete manufacturing
first order logic axiom: WorkCell(x) → WorkUnit(x) ∧ ∃y(ProductionLine(y) ∧ memberPartOfAtSomeTime(x, y))
is primitive: true
natural language definition: work unit that is a member part of a production line and is used to manufacture some material parts that share manufacturing requirements
primitive rationale: There are insufficient constructs to provide a set of necessary and sufficient conditions. Specifically the construct 'manufacturing requirement' is missing.
semi formal natural language axiom: if x is a 'work cell' then x is a 'work unit' and x is a 'member part of at some time' some 'production line'

work center
type: Class
subclass of: BFO_0000027
subclass of: Restriction
  on property: BFO_0000115
  all values from: Class
    union of: Agent
    union of: PieceOfEquipment
subclass of: Restriction
  on property: hasCapability
  some values from: Class
    intersection of: Capability
    intersection of: Restriction
      on property: BFO_0000218
      some values from: Class
        union of: Agent
        union of: PieceOfEquipment
example: process cell; production line; production unit; storage zone
adapted from: ISA95
explanatory note: 1. A work center's capabilities are determined by one or more of its constituent members, which is formally represented using the 'has material basis' axiom. 2. Work centers are typically within (member parts of) a physical area or physical site, reflecting their spatial and organizational context.
first order logic axiom: WorkCenter(x) → ObjectAggregate(x) ∧ ∃y((Agent(y) ∨ PieceOfEquipment(y)) ∧ hasMemberPartAtSomeTime(x,y) ∧ ∃c(Capability(c) ∧ hasCapability(x,c) ∧ hasMaterialBasisAtSomeTime(c,y)))
is primitive: true
natural language definition: object aggregate that has piece of equipment or agent as its member parts
primitive rationale: This term is expected to remain primitive as it will be challenging to specify the exact grouping criteria that would unambigously differentiate the work center from any other grouping of agents or equipment
semi formal natural language axiom: if x is a 'work center', then x is an 'object aggregate' that 'has member part at some time some' y, where y is either an 'agent' or a 'piece of equipment', and x 'has capability' some 'capability' that 'has material basis at some time' y

work unit
type: Class
subclass of: BFO_0000027
equivalent class: Class
  intersection of: BFO_0000027
  intersection of: Restriction
    on property: BFO_0000173
    some values from: work center
example: physical unit; storage unit; work cell
adapted from: ISA 95
explanatory note: ISA 95: any element in the equipment hierarchy under the work center
first order logic definition: WorkUnit(x) ↔ ObjectAggregate(x) ∧ ∃y(WorkCenter(y) ∧ memberPartOfAtAllTimes(x, y))
natural language definition: object aggregate that is a member of a work center
semi formal natural language definition: every instance of a 'work unit' is defined as exactly an instance of 'object aggregate' that is the 'member part of at all times' some 'work center'