IfcKnotType

BACnet MVD

#### IfcKnotType

Natural language names

| Knot Type
| Type de nœud

Change log

Item | SPF | XML | Change | Description
--- | --- | --- | --- | ---
IFC2x3 to IFC4
IfcKnotType |  |  | ADDED |

##### Semantic definitions at the type

Type definition

The IfcKnotType indicates the particular form of b-spline knots.

> NOTE Definition according to ISO/CD 10303-42:1992
> This type indicates that the B-spline knots shall have a particularly simple form enabling the knots themselves to be defaulted.

> NOTE Type adapted from knot_type defined in ISO 10303-42.

> HISTORY New type in IFC4.

Enumeration definition

Constant | Description
--- | ---
UNIFORM_KNOTS | The form of knots appropriate for a uniform B-spline curve.
QUASI_UNIFORM_KNOTS | The form of knots appropriate for a quasi-uniform B-spline curve.
PIECEWISE_BEZIER_KNOTS | The form of knots appropriate for a piecewise Bezier curve.
UNSPECIFIED | The type of knots is not specified. This includes the case of non uniform knots.

##### Formal representations

XML Specification
`<xs:simpleType name="IfcKnotType">
<xs:restriction base="xs:string">
<xs:enumeration value="uniform_knots"/>
<xs:enumeration value="quasi_uniform_knots"/>
<xs:enumeration value="piecewise_bezier_knots"/>
<xs:enumeration value="unspecified"/>
</xs:restriction>
</xs:simpleType>
`
EXPRESS Specification
`TYPE IfcKnotType = ENUMERATION OF (
UNIFORM_KNOTS,
QUASI_UNIFORM_KNOTS,
PIECEWISE_BEZIER_KNOTS,
UNSPECIFIED);
END_TYPE;

EXPRESS-G diagram

`

References: IfcBSplineCurveWithKnots IfcBSplineSurfaceWithKnots

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