གཙུག་ལག། རྩ་ལག། ཡན་ལག།

gtsug lag, rtsa lag, yan lag:

Could it be that both gtsug lag and rtsa lag contain yan lag? Perhaps gtsug lag = “crown/crest” (gtsug) +  “limb” (yan lag) = a higher constellation with spiritual/scientific relevance (e.g. temple, science, or scientific treatise)? rtsa lag = “root” (rtsa ba) + “limb” (yan lag) = a lower constellation with mundane/familiar relevance (e.g. kindred)? Note also cha lag.

Cf. brDa dkrol (s.v.): ’phags pa’i gtsug nas bton te zhu byed kyi lag tu bzhag pas…. This is truly a folk  etymology and I do not consider it plausible at all. Such an etymology has been ridiculed by Tshe-tan-zhabs-drung, Thon mi’i zhal lung (p. 64).

For articles on the term gtsug lag, see http://earlytibet.com/category/bon/page/2/.