# 3 Terms, definitions, and abbreviated terms

## 3.1 Terms and definitions

For the purpose of this document, the following definitions apply.

attribute

unit of information within an entity, defined by a particular type or reference to a particular entity

1. NOTE There are three kinds of attributes: direct attributes, inverse attributes and derived attributes.

direct attribute

scalar values or collections including Set (unordered, unique), List (ordered), or Array (ordered, sparse) as defined in [ISO 10303-11]

1. NOTE Similar to the term "field" in common programming languages.

inverse attribute

unit of information defining queries for obtaining related data and enforcing referential integrity

1. NOTE Similar to the term "navigation property" in entity-relational programming frameworks.

derived attribute

unit of information computed from other attributes using an expression defined in the schema

constraints on attributes

data type restricting the values of attributes

1. NOTE 1 The most general constraint is about the existence of attribute values. There are basically two types: mandatory and optional attributes. Values of mandatory attributes must be provided whereas values of optional attributes may be omitted.
2. NOTE 2 For aggregation data types such as Set, List, or Array, the existence constraint is often refined by a minimal and maximal number of elements, which is also known as cardinality.

entity

class of information defined by common attributes and constraints as defined in [ISO 10303-11]

1. NOTE Similar to the term "class" in common programming languages but describing data structure only (not behavior such as methods).

identification

capability to find, retrieve, report, change, or delete specific instances without ambiguity

instance

occurrence of an entity

1. NOTE Similar to the term "instance of a class" in object oriented programming.

object

anything perceivable or conceivable that has a distinct existence, albeit not material

type

basic information construct derived from a primitive, an enumeration, or a select of entities

1. NOTE 1 Similar to the "Type" construct as defined in [ISO 10303-11].
2. NOTE 2 Similar in concept to "typedef" or "value type" in common programming languages.

select

construct that allows an attribute value to be one of multiple types or entities

1. NOTE 1 Similar to the "Select" construct as defined in [ISO 10303-11].
2. NOTE 2 Similar to a "marker interface" in common programming languages.

enumeration

construct that allows an attribute value to be one of multiple predefined values identified by name

1. NOTE 1 Similar to the "Enumeration" construct as defined in [ISO 10303-11].
2. NOTE 2 Similar in concept to "enum" in common programming languages.

actor

person, an organization, or person acting on behalf of an organization

1. NOTE A specialization of the general term object.

classification

categorization, the act of distributing things into classes or categories of the same type

constraint

restriction for a specified reason

1. NOTE A specialization of the general term control.

control

directive to meet specified requirements such as for scope, time, and/or cost

1. NOTE A specialization of the general term object.

dictionary

collection of words, terms or concepts, with their definition

element

tangible physical product that can be described by its shape representation, material representations, and other properties

1. NOTE A specialization of the general term product.

element occurrence

element's position within the project coordinate system and its containment within the spatial structure

external reference

link to information outside the data set, with direct relevance to the specific information the link originates from inside the data set

feature

parametric information and additional property information modifiying the shape representation of an element to which it applies

group

collection of information that fulfills a specified purpose

1. NOTE A specialization of the general term object.

library

catalogue, database or holder of data, that is relevant to information in the data set

1. NOTE It is information referenced from an external source that is not copied into the data set.

object occurrence

characteristics of an object as an individual

1. NOTE Similar to "object", "instance", "individual" in other publications.

object type

common characteristics shared by multiple object-occurrences

1. NOTE Similar to "class", "template", "type" in other publications.

process

object-occurrence located in time, indicating "when"

process occurrence

conceptual object that may occur at a particular time

process type

common characteristics shared by multiple process occurrences

product

physical or conceptual object that occurs in space

1. NOTE It is specialization of the general term object.

product occurrence

physical or conceptual object that may have a location in space and shape characteristics

product type

common characteristics shared by multiple product occurrences

project

encapsulation of related information for a particular purpose providing context for information contained within

1. NOTE Context information may include default measurement units or representation context and precision.

property

unit of information that is dynamically defined as a particular entity instance

1. NOTE Similar to "late-bound" or "run-time" in programming terminology.

property occurrence

unit of information providing a value for a property identified by name

property template

metadata for a property including name, description, and data type

1. NOTE Similar in concept to "extension property" in common programming languages.

property set occurrence

unit of information containing a set of property occurrences, each having a unique name within the property set

property set template

set of property templates serving a common purpose and having applicability to objects of a particular entity

1. NOTE Similar in concept to "extension class" in common programming languages.

proxy

object that does not hold a specific object type information

1. NOTE a specialization of object occurrence.

quantity

measurement of a scope-based metric, specifically length, area, volume, weight, count, or time

quantity occurrence

unit of information providing a value for a quantity

quantity set

unit of information containing a set of quantity occurrences, each having a unique name within the quantity set

relationship

unit of information describing an interaction between items

representation

unit of information describing how an object is displayed, such as physical shape or topology

resource

entity with limited availability such as materials, labor, or equipment

1. NOTE 1 a specialization of the general term object.
2. NOTE 2 the "resource definition data schemas" section is unrelated to this concept.

resource occurrence

entity with inherent financial cost, which may be passed onto processes, products, and controls to which it is assigned

resource type

common characteristics shared by multiple resource occurrences

space

area or volume bounded actually or theoretically

1. NOTE a specialization of the general term product.

## 3.2 Abbreviated terms

For the purpose of this document, the following abbreviated terms apply:

AEC | Architecture, Engineering, and Construction
AEC/FM | Architecture, Engineering, Construction, and Facilities Management
BIM | Building Information Modeling
GUID | Globally Unique Identifier
IFC | Industry Foundation Classes
IFD | International Framework for Dictionaries
SPF | STEP Physical File
STEP | STandard for the Exchange of Product data
URI | Uniform Resource Identifier
UUID | Universally Unique Identifier