Cellulosic: xx10 and xx11
Rutil: xx12, xx13 and xx14
Basic: xx15, xx16, xx18
etc..
More over DEANC is right about the "1".
"1" means you can weld on all position, becarful it is not right all the time.
But if you have "2" in lieu of "1", that means you can weld only on flat position and horizontal fillet.
For your application the electrode E7018 is a real standard as basic eletrode.