▁with ▁sil at ▁training ▁in ▁general , ▁was ▁often ▁done ▁in ▁varying ▁conditions ▁to ▁prepare ▁the ▁f ighter ▁for ▁combat ▁in ▁any ▁situation . ▁The ▁most ▁common ▁of ▁these ▁was ▁training ▁in ▁dim ▁light , ▁sp arring ▁against ▁several ▁oppon ents , ▁fighting ▁un ar med ▁against ▁a ▁weap oned ▁oppon ent , ▁and ▁fighting ▁in ▁darkness ▁or ▁blind fold ed . ▁O thers ▁include ▁fighting ▁in ▁a ▁tight ▁space ▁( common ▁in ▁B aj au ▁styles ), ▁on ▁a ▁sli pp ery ▁surface ▁( as ▁in ▁Min ang ▁styles ), ▁or ▁from ▁a ▁se ated ▁position ▁( a ▁fundamental ▁of ▁S unda ▁styles ). ▁Exper ien ced ▁pract ition ers ▁may ▁fight ▁against ▁up ▁to ▁twelve ▁oppon ents , ▁a ▁practice ▁known ▁as ▁k ero j ok ▁in ▁J avan ese . ▁The ▁def ender ▁is ▁attacked ▁by ▁both ▁armed ▁and ▁un ar med ▁oppon ents . ▁We ap ons ▁can ▁be ▁inter changed ▁between ▁the ▁attack ers , ▁while ▁the ▁def ender ▁is ▁allowed ▁to ▁ste al ▁and ▁use ▁the ▁weapons ▁against ▁them . ▁These ▁matches ▁were ▁tradition ally ▁full - contact ▁and ▁highly ▁dangerous , ▁but ▁are ▁generally ▁kept ▁light - contact ▁today . ▁ ▁Test s ▁Advanced ▁sil at ▁students ▁under go ▁or de als ▁or ▁u j ian ▁meant ▁to ▁test ▁their ▁physical , ▁psych ological ▁and ▁spiritual ▁end urance . ▁In ▁former ▁times , ▁these ▁tests ▁were ▁sometimes ▁even ▁used ▁as ▁a ▁way ▁of ▁seeing ▁whether ▁the ▁student ▁is ▁willing ▁to ▁follow ▁the ▁master ' s ▁instructions