#### IfcSIPrefix

Natural language names

##### Semantic definitions at the type

Type definition

Definition from ISO/CD 10303-41:1992: An SI prefix is the name of a prefix that may be associated with an SI unit. The definitions of SI prefixes are specified in ISO 1000 (clause 3).

> NOTE The prefix defines multiples and submultiples of the SI units.

> NOTE Corresponding STEP name: SI_prefix, please refer to ISO/IS 10303-41:1994 for the final definition of the formal standard.

ENUMERATION

- EXA 10^18.
- PETA 10^15.
- TERA 10^12.
- GIGA 10^9.
- MEGA 10^6.
- KILO 10^3.
- HECTO 10^2.
- DECA 10.
- DECI 10^-1.
- CENTI 10^-2.
- MILLI 10^-3.
- MICRO 10^-6.
- NANO 10^-9.
- PICO 10^-12.
- FEMTO 10^-15.
- ATTO 10^-18.

> HISTORY New entity in IFC Release 1.5.1.

Enumeration definition

Constant | Description
--- | ---
EXA |
PETA |
TERA |
GIGA |
MEGA |
KILO |
HECTO |
DECA |
DECI |
CENTI |
MILLI |
MICRO |
NANO |
PICO |
FEMTO |
ATTO |

##### Formal representations

XSD Specification
`<xs:simpleType name="IfcSIPrefix">
<xs:restriction base="xs:string">
<xs:enumeration value="exa"/>
<xs:enumeration value="peta"/>
<xs:enumeration value="tera"/>
<xs:enumeration value="giga"/>
<xs:enumeration value="mega"/>
<xs:enumeration value="kilo"/>
<xs:enumeration value="hecto"/>
<xs:enumeration value="deca"/>
<xs:enumeration value="deci"/>
<xs:enumeration value="centi"/>
<xs:enumeration value="milli"/>
<xs:enumeration value="micro"/>
<xs:enumeration value="nano"/>
<xs:enumeration value="pico"/>
<xs:enumeration value="femto"/>
<xs:enumeration value="atto"/>
</xs:restriction>
</xs:simpleType>
`
EXPRESS Specification
`TYPE IfcSIPrefix = ENUMERATION OF (
EXA,
PETA,
TERA,
GIGA,
MEGA,
KILO,
HECTO,
DECA,
DECI,
CENTI,
MILLI,
MICRO,
NANO,
PICO,
FEMTO,
ATTO);
END_TYPE;

EXPRESS-G diagram

`

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