The centering operation is important because the diameter of a knit tube varies slightly along its length, and it is necessary to reference cutting from the midline of the tube.
( ( ( ( ( ( The ( centering operation ) ) ( ( is important ) ( because ( ( ( the diameter ) ( of ( a ( knit tube ) ) ) ) ( ( varies slightly ) ( along ( its length ) ) ) ) ) ) ) , ) and ) ( it ( is ( necessary ( to ( reference ( cutting ( from ( ( the midline ) ( of ( the tube ) ) ) ) ) ) ) ) ) ) ) . )
(ROOT (S (S (NP (DT The) (JJ centering) (NN operation)) (VP (VBZ is) (ADJP (JJ important)) (SBAR (IN because) (S (NP (NP (DT the) (NN diameter)) (PP (IN of) (NP (DT a) (JJ knit) (NN tube)))) (VP (VBZ varies) (ADVP (RB slightly)) (PP (IN along) (NP (PRP$ its) (NN length)))))))) (, ,) (CC and) (S (NP (PRP it)) (VP (VBZ is) (ADJP (JJ necessary) (S (VP (TO to) (VP (VB reference) (S (VP (VBG cutting) (PP (IN from) (NP (NP (DT the) (NN midline)) (PP (IN of) (NP (DT the) (NN tube))))))))))))) (. .)))
The centering operation is pointless.
( ( The ( centering operation ) ) ( ( is pointless ) . ) )
(ROOT (S (NP (DT The) (JJ centering) (NN operation)) (VP (VBZ is) (ADJP (JJ pointless))) (. .)))