By default V606/6.5.5 will run the new code.
The user can make it run the old V605 code by adding "UseOlderRTFImportExport=1" to Notes.ini. Release 6.x, from 6.5.5 on, will have this dual RTF converter capability. Starting with 7.0, only the new RTF conversion code will be present. This regression was introduced in 6.0.3.