The content of the database is called the Reference Data.
It contains mostly core classes, but also reference individuals.
A class describes an aspect of a group of objects. A class is an understanding of the nature of things and that divides things into those which are members of the class and those which are not according to one or more criteria.
A core class is a class that is a commonly used subdivision corresponding to terms used in common language.
The conditions for membership are often not formally
defined; understanding of the class may be conveyed by example.
Examples: Pipe, floor, pump, and light bulb are core classes.
A reference individual an individual which is commonly referred to.
Examples: the city of London, the company Wal-Mart are reference individuals.
ISO 15926 knows 201 types of classes and individuals.
Examples of these are:
class of activity
hydrostatic testing, archiving, process engineering,
transforming
class of atom
Nickel, Neon, Uranium-238
class of class of individual
these are group definitions
DIN 961 bolt class, duplex steel piping class, piping class
300 lbs
class of compound
ferritic austenitic stainless steel, ASTM A 240/A 240M - S44500, thermoplastic, marine gas oil
class of feature
countersunk rivet head, valve orifice, pipeline upheaval
buckle
class of functional object
restricted area, fluid mixer, gas pressure increasing device
class of inanimate physical object
ROV operated valve, field weld, centrifugal compressor, ASTM
A 333/A 333M - grade 1 seamless pipe
class of information object
P&ID, equipment list, gas log, material certificate, operation
directive, single-line diagram
class of molecule
p-menthane hydroperoxide,
n-hexyl-1,2,3,4-tetrahydronaphthalene
class of organization
EPC contractor, discipline, accreditation company
class of status
failure mode
status
open, painted, uncoated, approved, old, new, worn, hazardous, safe, dangerous, rusty
single property dimension
maximum pressure, electrical frequency, operating weight,
linear velocity, leakage rate