The problem was solved simply by using an already standard character that had a similar sound to what the Viet called themselves.
( ( The problem ) ( ( was ( ( solved simply ) ( by ( using ( ( an ( already ( standard character ) ) ) ( that ( had ( ( a ( similar sound ) ) ( ( to what ) ( ( the Viet ) ( called themselves ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN problem)) (VP (VBD was) (VP (VBN solved) (ADVP (RB simply)) (PP (IN by) (S (VP (VBG using) (NP (NP (DT an) (RB already) (JJ standard) (NN character)) (SBAR (WHNP (WDT that)) (S (VP (VBD had) (NP (NP (DT a) (JJ similar) (NN sound)) (SBAR (WHPP (TO to) (WHNP (WP what))) (S (NP (DT the) (NNP Viet)) (VP (VBD called) (NP (PRP themselves))))))))))))))) (. .)))
Characters are generally interchangeable as long as they sound the same.
( Characters ( ( are ( ( ( generally interchangeable ) ( as long ) ) ( as ( they ( sound ( the same ) ) ) ) ) ) . ) )
(ROOT (S (NP (NNS Characters)) (VP (VBP are) (ADJP (ADJP (RB generally) (JJ interchangeable)) (ADVP (RB as) (RB long)) (SBAR (IN as) (S (NP (PRP they)) (VP (VB sound) (NP (DT the) (JJ same))))))) (. .)))