▁of ▁the ▁pat ent ▁extends ▁beyond ▁the ▁content ▁of ▁the ▁application ▁as ▁file d . ▁The ▁notice ▁of ▁opposition ▁to ▁a ▁European ▁pat ent ▁must ▁be ▁file d ▁in ▁writing ▁at ▁the ▁E PO ▁( e ither ▁at ▁Mun ich , ▁The ▁H ague ▁or ▁Berlin ), ▁along ▁with ▁the ▁payment ▁of ▁an ▁opposition ▁fee , ▁within ▁nine ▁months ▁from ▁the ▁publication ▁of ▁the ▁mention ▁of ▁the ▁grant ▁of ▁the ▁pat ent ▁in ▁the ▁European ▁Pat ent ▁Bul letin . ▁O pp osition ▁Div isions ▁of ▁the ▁E PO ▁are ▁responsible ▁for ▁the ▁exam ination ▁of ▁oppos itions . ▁The ▁opposition ▁procedure ▁may ▁involve ▁multiple ▁oppon ents . ▁According ▁to ▁the ▁E PO , ▁a ▁European ▁pat ent ▁was ▁once ▁opposed ▁by ▁a ▁record ▁number ▁of ▁ 2 7 ▁oppon ents . ▁ ▁Pur pose , ▁framework , ▁and ▁available ▁grounds ▁ ▁The ▁purpose ▁of ▁the ▁opposition ▁proceed ings ▁is ▁to ▁give ▁oppon ents , ▁such ▁as ▁compet itors , ▁the ▁opportunity ▁to ▁challenge ▁the ▁valid ity ▁of ▁a ▁granted ▁European ▁pat ent . ▁O pp on ents ▁may ▁also ▁challenge ▁only ▁some ▁of ▁the ▁claims ▁of ▁the ▁European ▁pat ent ▁( although ▁this ▁is ▁in ▁practice ▁rather ▁unusual ), ▁therefore ▁limit ing ▁the ▁framework ▁of ▁the ▁opposition ▁to ▁the ▁challeng ed ▁claims . ▁ ▁However , ▁an ▁opposition ▁can ▁only ▁be ▁based ▁on ▁a ▁limited ▁number ▁of ▁grounds ▁( i . e ., ▁ob jections ) ▁specified ▁in ▁the ▁European ▁Pat ent ▁Convention , ▁namely ▁the ▁grounds ▁listed ▁in ▁. ▁An ▁opposition