IfcBoundingBox定义了一个与定义它的对象坐标系的轴平行的正交长方体。它是由一个角点定义的，角点是三维笛卡尔点，三个长度度量值定义盒子在正轴方向上的X、Y和Z参数。
注意，具有产品形状表示的IfcProduct的任何子类型都可能具有边界框表示。在IfcShapeRepresentation中定义的“Box”表示标识符使用IfcBoundingBox作为最简单的三维形状表示。
如图所示，IfcBoundingBox定义有自己的位置，可以用来相对于几何坐标系放置IfcBoundingBox。IfcBoundingBox由左下角（角）和右上角（在父坐标系中测量的XDim、YDim和ZDim）定义。
| # | Attribute | Type | Cardinality | Description | C |
|---|---|---|---|---|---|
| IfcRepresentationItem | |||||
| LayerAssignment | IfcPresentationLayerAssignment @AssignedItems |
S[0:1] | Assignment of the representation item to a single or multiple layer(s). The LayerAssignments can override a LayerAssignments of the IfcRepresentation it is used within the list of Items. | X | |
| StyledByItem | IfcStyledItem @Item |
S[0:1] | Reference to the IfcStyledItem that provides presentation information to the representation, e.g. a curve style, including colour and thickness to a geometric curve. | X | |
| IfcGeometricRepresentationItem | |||||
| IfcBoundingBox | |||||
| 1 | Corner | IfcCartesianPoint | [1:1] | Location of the bottom left corner (having the minimum values). | X |
| 2 | XDim | IfcPositiveLengthMeasure | [1:1] | Length attribute (measured along the edge parallel to the X Axis) | X |
| 3 | YDim | IfcPositiveLengthMeasure | [1:1] | Width attribute (measured along the edge parallel to the Y Axis) | X |
| 4 | ZDim | IfcPositiveLengthMeasure | [1:1] | Height attribute (measured along the edge parallel to the Z Axis). | X |
| Dim :=3 |
IfcDimensionCount | [1:1] | The space dimensionality of this class, it is always 3. | X | |
EXPRESS Specification
ENTITY IfcBoundingBox
SUBTYPE OF (IfcGeometricRepresentationItem);
Corner : IfcCartesianPoint;
XDim : IfcPositiveLengthMeasure;
YDim : IfcPositiveLengthMeasure;
ZDim : IfcPositiveLengthMeasure;
DERIVE
Dim : IfcDimensionCount := 3;
END_ENTITY;