coref ocref croef rcoef orcef rocef coerf ocerf ceorf ecorf oecrf eocrf creof rceof cerof ecrof recof ercof orecf roecf oercf eorcf reocf erocf corfe ocrfe crofe rcofe orcfe rocfe cofre ocfre cfore fcore ofcre focre crfoe rcfoe cfroe fcroe rfcoe frcoe orfce rofce ofrce force rfoce froce coefr ocefr ceofr ecofr oecfr eocfr cofer ocfer cfoer fcoer ofcer focer cefor ecfor cfeor fceor efcor fecor oefcr eofcr ofecr foecr efocr feocr crefo rcefo cerfo ecrfo recfo ercfo crfeo rcfeo cfreo fcreo rfceo frceo cefro ecfro cfero fcero efcro fecro refco erfco rfeco freco efrco ferco orefc roefc oerfc eorfc reofc erofc orfec rofec ofrec forec rfoec froec oefrc eofrc oferc foerc eforc feorc refoc erfoc rfeoc freoc efroc feroc
Note: these 'words' (valid or invalid) are all the permutations of the word coref. These words are obtained by scrambling the letters in coref.