The window lining is the outer frame which enables the window to be fixed in position. The window lining is used to hold the window panels or other casements. The parameter of the IfcWindowLiningProperties define the geometrically relevant parameter of the lining. 

The IfcWindowLiningProperties are included in the set of properties of IfcWindowStyle.HasPropertySets. More information about the window lining can be included in the same set of the IfcWindowType using another IfcPropertySet for dynamic extensions. 

The IfcWindowLiningProperties does not hold a geometric representation. However it defines parameters which can be used to create the shape of the window type (which is inserted by the IfcWindow into the spatial context of the project). The parameters at the IfcWindowLiningProperties define a standard window lining, including (if given) a mullion and a transom (for horizontal and vertical splits). The outer boundary of the lining is determined by the 'Profile' shape representation assigned to the IfcWindow, which inserts the IfcWindowType.

• The lining is applied to all faces of the opening reveal. The parameters are:
  • LiningDepth
  • LiningThickness
  • LiningOffset
  • LiningToPanelOffsetX
  • LiningToPanelOffsetY

The inner side is defined as the direction of the window panel opening operation. 

• If the OperationType of the window style is
  • DoublePanelVertical (shown)
  • TriplePanelBottom
  • TriplePanelTop
  • TriplePanelLeft
  • TriplePanelRight

the following additional parameters apply:

• MullionThickness
• FirstMullionOffset measured as offset to the Z axis (in XZ plane) as a normalized ratio measure

• If the OperationType of the window type is:
  • DoublePanelHorizontal
  • TriplePanelBottom
  • TriplePanelTop
  • TriplePanelLeft
  • TriplePanelRight

the following additional parameters apply:

• TransomThickness
• FirstTransomOffset measured as offset to the X axis (in XZ plane) as a normalized ratio measure

• If the OperationType of the window type is:
  • TriplePanelVertical

the following additional parameter applies:

• SecondMullionOffset measured as offset to the Z axis (in XZ plane) as a normalized ratio measure

• If the OperationType of the window type is:
  • TriplePanelHorizontal

the following additional parameter applies:

• SecondTransomOffset measured as offset to the X axis (in XZ plane) as a normalized ratio measure