The HFMwCustom3 component contains the dimension property. This component enables you to work with the Custom 3 dimension.
Obtaining an HFMwCustom3 Object Reference
HFMwCustom3 object references are returned by the custom3 property of the HFMwMetadata component. After obtaining an HFMwCustom3 object reference, you can then use the dimension property to initialize the HFMwDimension component to the Custom 3 dimension.