drdis rddis ddris ddris rddis drdis drids rdids dirds idrds ridds irdds ddirs ddirs didrs iddrs didrs iddrs rdids drids ridds irdds dirds idrds drdsi rddsi ddrsi ddrsi rddsi drdsi drsdi rdsdi dsrdi sdrdi rsddi srddi ddsri ddsri dsdri sddri dsdri sddri rdsdi drsdi rsddi srddi dsrdi sdrdi drisd rdisd dirsd idrsd ridsd irdsd drsid rdsid dsrid sdrid rsdid srdid disrd idsrd dsird sdird isdrd sidrd risdd irsdd rsidd sridd isrdd sirdd ddisr ddisr didsr iddsr didsr iddsr ddsir ddsir dsdir sddir dsdir sddir disdr idsdr dsidr sdidr isddr siddr disdr idsdr dsidr sdidr isddr siddr rdisd drisd ridsd irdsd dirsd idrsd rdsid drsid rsdid srdid dsrid sdrid risdd irsdd rsidd sridd isrdd sirdd disrd idsrd dsird sdird isdrd sidrd
Note: these 'words' (valid or invalid) are all the permutations of the word drdis. These words are obtained by scrambling the letters in drdis.