worldDraw() or viewportDraw() calls from different threads are allowed for highest level (MS or PS), elsewhere they should always happen in one dedicated thread.
kMTRenderInBlock
Calls to worldDraw() or viewportDraw() methods from different threads are allowed if the drawable is located inside a block (compound object).
kMTRenderNested
worldDraw() or viewportDraw() from different threads are allowed for nested drawables of this compound object.
kMTRenderReserved
Reserved for future use.
kMTRenderMask
Combination of all MTRender-dependent flags.
kMTLoading
Multithread loading is supported for this object.
kHistoryAware
The information written by the object to the undo filer can be saved in the history file (is valid between sessions)