( ( Each ( blood type ) ) ( ( ( is also ) ( grouped ( by ( ( ( ( ( its ( Rhesus factor ) ) , ) or ) ( Rh factor ) ) ( -LRB- ( ( ( another type ) ( of antigen ) ) -RRB- ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT Each) (NN blood) (NN type)) (VP (VBZ is) (ADVP (RB also)) (VP (VBN grouped) (PP (IN by) (NP (NP (PRP$ its) (NNP Rhesus) (NN factor)) (, ,) (CC or) (NP (NNP Rh) (NN factor)) (PRN (-LRB- -LRB-) (NP (NP (DT another) (NN type)) (PP (IN of) (NP (NN antigen)))) (-RRB- -RRB-)))))) (. .)))
Each blood type is also grouped by its Rhesus factor, or Rh factor (another type of antigen).
(ROOT (S (NP (NNP Rh)) (VP (VBZ is) (NP (NP (DT the) (JJ common) (NN abbreviation)) (PP (IN for) (S (VP (VBG noting) (NP (DT the) (JJ rhesus) (NN blood) (NN type))))))) (. .)))