Host block-table record name to associate with this overlay.
OptionalcontentRaw DWG/DXF bytes; used when sourceDb is not provided.
File name passed to the overlay loader when content is used.
OptionalinsertWhen set, associates the session with an existing host INSERT.
OptionalsourceWhen set, skips a second file read and uses this database for rendering.
Source file path or display name stored on the session.
OptionaltransformOptional transform applied to the overlay layout after load.
Options for attaching a read-only xref overlay via AcApXrefManager.attachOverlay.
Provide either sourceDb or content; if both are absent, attach fails.