Hi guys,
seems the creatattrib SOP can pass an arbitrary property to mantra, but i dont know when should i add an proper attribute.

e.g in the grass scene file attached,why adding attibutes called rootcolor and tipcolor,clump etc, mantra can recognize them as curves' root and tip properties.and where can I find these hiden attrib in houdini's help document.

the hip file may make my question clear.