Cut-plane line style (elements intersected by the section plane)
Solid fill color for the cut polygon face. null = transparent
Hatch/pattern overlay applied on top of the fill. null = no hatch
Human-readable label (used in the Object Styles UI table)
Below-cut projection line style
Whether this category appears in 2D views at all
Full graphic style for one IFC element category. Optional fields fall back to
DEFAULT_OBJECT_STYLES['_default'].