tatra rūpamavijñātam, kimayameva varṇo 'thānyo viśeṣa eva varṇakrama uta neti svataḥ parataś ca niścayāyogāt /
There, the form is unknown because one cannot determine, either by oneself or through others, whether this is indeed the [correct] letter or some other letter, or whether this is indeed the [correct] sequence of letters or not.