Stephan Beyer in general seems to speak of two types of words, namely, (a) semantically endocentric and non-lexicalised words whose meanings are predictable (i.e. obvious) and (b) semantically exocentric and lexicalised words whose meanings are unpredictable (i.e. not obvious). As an example of the former rdo ril “round stone” is given, and as the example of the latter, rdo zho, which etymologically means “stone milk” (but perhaps better “stone curd”) and semantically means “lime,” is mentioned. The former is of no interest to lexicographers whereas the latter is. For a long discussion on this, see Beyer 1992: 101–102, n. 4. He admits, however, that the distinction between the two is not always entirely clear.