    <!--Single-->			  <layout name="13056" type="layout" possibleCyl="13076"              possibleFuel="13103/13104/XXXXa/XXXXB"
		<!--Straight-->			<layout name="13057" type="layout" possibleCyl="13077/13078/13079"  possibleFuel="13103/13104/XXXXa/XXXXB"
		<!--V-->			    	<layout name="13059" type="layout" possibleCyl="13077/13079"        possibleFuel="13103/13104/XXXXa/XXXXB"
    etc...

    <!--Single-Cylinder-->		<cylinder name="13076" type="cylinder"
		<!--2-->					        <cylinder name="13077" type="cylinder"
		<!--3-->					        <cylinder name="13078" type="cylinder"
		<!--4-->				        	<cylinder name="13079" type="cylinder"
    etc...

		<!--4-Stroke Gas-->		<fuel name="13103" type="fuel" possibleValve="13268/13271/13272" 
		<!--Diesel-->			    <fuel name="13104" type="fuel" possibleValve="13268/13271/13272" 
    <!--2-Stroke Gas-->   <fuel name="XXXXA" type="fuel" possibleValve="XXXX1/XXXX2/XXXX3/XXXX4/XXXX5"
    <!--2-Stroke Diesel--><fuel name="XXXXB" type="fuel" possibleValve="XXXX1/XXXX2/XXXX3/XXXX4/XXXX5"					
    etc..
	
    <!--None -->			<valve name=""      type="valve" 
    <!--T -->					<valve name="13268" type="valve"
    <!--OHV -->				<valve name="13271" type="valve" 
    <!--SOHC -->			<valve name="13272" type="valve"
    etc..

    <!--PistonCtrl--> <valve name="XXXX1" type="valve" 
    <!--Reed-->       <valve name="XXXX2" type="valve" 
    <!--Rotary-->     <valve name="XXXX3" type="valve" 
    <!--Crossflw-->   <valve name="XXXX4" type="valve" 
    <!--Schnuerle-->  <valve name="XXXX5" type="valve"
    etc..

- NOTE
I just noted the 'Valve="2"' under the engine layout and the 'limit="2"' under the valve type, I guess this is how possible valves are defined?

- NOTE
Most values deleted just to make it easier to make out the concept.