It is said that the Sautrāntikas, as opposed to Vaibhāṣikas, both of whom are said to be Bāhyārthavādins (i.e. Buddhist realists), posit that the external entities (e.g. stones) are not perceived or perceptible and remain remote or inaccessible (although their images, which are of the cognitive nature, are cognised). Such objects are said to be “covert” (lkog na mo). The term lkog na mo is interesting because it contains a frozen locative participle (na) and a nominaliser (mo). The term can be found in the Tshig mdzod chen mo although its meaning lkog gyur (cognitively remote), in my view, is not correct, because for the Sautrāntikas external objects by definition are lkog na mo but not necessarily lkog gyur insofar as they can still be the objects of direct perception (mngon sum) and thus mngon gyur (“manifest or conspicuous”). A direct opposite of lkog na mo seems to be mdun na mo, which can perhaps be rendered as “overt.” The term mdun na mo has been recorded both in the Tshig mdzod chen mo and brDa dkrol (s.v.).