itlss tilss iltss litss tliss ltiss itsls tisls istls sitls tsils stils ilsts lists islts silts lsits slits tlsis ltsis tslis stlis lstis sltis itlss tilss iltss litss tliss ltiss itsls tisls istls sitls tsils stils ilsts lists islts silts lsits slits tlsis ltsis tslis stlis lstis sltis itssl tissl istsl sitsl tsisl stisl itssl tissl istsl sitsl tsisl stisl isstl sistl isstl sistl ssitl ssitl tssil stsil tssil stsil sstil sstil ilsst lisst islst silst lsist slist ilsst lisst islst silst lsist slist isslt sislt isslt sislt ssilt ssilt lssit slsit lssit slsit sslit sslit tlssi ltssi tslsi stlsi lstsi sltsi tlssi ltssi tslsi stlsi lstsi sltsi tssli stsli tssli stsli sstli sstli lssti slsti lssti slsti sslti sslti
Note: these 'words' (valid or invalid) are all the permutations of the word itlss. These words are obtained by scrambling the letters in itlss.