optco potco otpco topco ptoco tpoco opcto pocto ocpto copto pcoto cpoto otcpo tocpo octpo cotpo tcopo ctopo ptcoo tpcoo pctoo cptoo tcpoo ctpoo optoc potoc otpoc topoc ptooc tpooc opotc pootc ooptc ooptc pootc opotc otopc toopc ootpc ootpc toopc otopc ptooc tpooc potoc optoc topoc otpoc opcot pocot ocpot copot pcoot cpoot opoct pooct oopct oopct pooct opoct ocopt coopt oocpt oocpt coopt ocopt pcoot cpoot pocot opcot copot ocpot otcop tocop octop cotop tcoop ctoop otocp toocp ootcp ootcp toocp otocp ocotp cootp ooctp ooctp cootp ocotp tcoop ctoop tocop otcop cotop octop ptcoo tpcoo pctoo cptoo tcpoo ctpoo ptoco tpoco potco optco topco otpco pcoto cpoto pocto opcto copto ocpto tcopo ctopo tocpo otcpo cotpo octpo
Note: these 'words' (valid or invalid) are all the permutations of the word optco. These words are obtained by scrambling the letters in optco.