Hi Karsten,

check this manual
http://moi.maxsm.net/api/#_CoordinateFrame

If you want to use frames as input data you can use this code:

function Line()
{
	this.addInput("Start","frame");
	this.addInput("End","frame");
	this.addOutput("Out","objectlist");
}
Line.title = "Line";
Line.desc = "Line";

Line.prototype.onExecute = function()
{
	var start = this.getInputData(0, moi.VectorMath.createFrame());
	var end = this.getInputData(1, moi.VectorMath.createFrame());
	var factory = moi.command.createFactory( 'line' );
	factory.setInput(0, start.origin);
	factory.setInput(1, end.origin);
	var output = factory.calculate();
	this.setOutputData(0, output);
	factory.cancel();
}
LiteGraph.registerNodeType("Factories/Line", Line);

but it will be better if you use points instead of frames

function Line()
{
	this.addInput("Start","point");
	this.addInput("End","point");
	this.addOutput("Out","objectlist");
}
Line.title = "Line";
Line.desc = "Line";

Line.prototype.onExecute = function()
{
	var start = this.getInputData(0, moi.VectorMath.createPoint());
	var end = this.getInputData(1, moi.VectorMath.createPoint());
	var factory = moi.command.createFactory( 'line' );
	factory.setInput(0, start);
	factory.setInput(1, end);
	var output = factory.calculate();
	this.setOutputData(0, output);
	factory.cancel();
}
LiteGraph.registerNodeType("Factories/Line", Line);