The HFMwCustom4 component contains the dimension property. This component enables you to work with the Custom 4 dimension.
Obtaining an HFMwCustom4 Object Reference
HFMwCustom4 object references are returned by the custom4 property of the HFMwMetadata component. After obtaining an HFMwCustom4 object reference, you can then use the dimension property to initialize the HFMwDimension component to the Custom 4 dimension.