HeaderVariables Audit

acadrust::document::HeaderVariables — 232 total.

Pass (no matching feature)

ISOLINES — contour line count on curved surfaces (no curved wireframe generator yet)
surface_u_density / surface_v_density / surface_type — defaults for SURFACE / REVSURF / EDGESURF commands (those commands don't exist yet)
lens_length / camera_height / camera_display — perspective camera (no perspective viewport yet)
north_direction / latitude / longitude / timezone — sun / geographic data (no sun-shadow renderer)
LIMMIN/LIMMAX — drawing limits (no bounded-grid mode)
INSBASE — drawing's "save as block" anchor (no WBLOCK / "save selection as block" flow)

~70 dim_* defaults — render-time DimStyle reference is already authoritative; these only seed a new DimStyle when a fresh DIMSTYLE NEW flow is added.
*_control_handle, *_dict_handle — internal table-navigation handles; direct document.layers / document.dim_styles / etc. accessors bypass them. acadrust read/write preserves them.
AutoCAD UI prefs (blip_mode, drag_mode, pick_style, etc.) — H7CAD has its own UI prefs and ignores AutoCAD's. Round-tripped.