By using Ring Circle script as a "template" guide for Frame, have succeeded in creating
arcFactory1 and arcFactory2, by script, showing on screen as two intersecting semicircles of 180 degrees.

Now I have a type mismatch in the following:

var myArcList = moi.geometryDatabase.createObjectList();
//NEXT LINE TYPE MISMATCH
myArcList.addObject( arcFactory1 );
myArcList.addObject( arcFactory2 );
var tanPtfactory = moi.command.createFactory( 'intersect' );
tanPtfactory.setInput( 0, myArcList );
tanPtfactory.commit();

I need to turn arcFactory1, an array ?, into a curve. ??

Maybe I need to use Factory '.calculate' method instead of update or commit, on arcFactory1. ?
Will try again tomorrow...