-yotl.

Headword: 
-yotl.
Principal English Translation: 

having the nature of; an abstract or collective nominal suffix that, when possessed, expresses inalienable or organic possession of the noun
James Lockhart, Nahuatl as Written: Lessons in Older Written Nahuatl, with Copious Examples and Texts (Stanford: Stanford University Press and UCLA Latin American Studies, 2001), 242.

Orthographic Variants: 
-iotl, -yo, -io
Attestations from sources in English: 

With organic possession, or inalienable possession, we can see the difference between nonac (my meat, as in, on my plate) and nonacayo (my body, or my flesh, a common testamentary term), or between īezhui (its blood, perhaps the meal of a blood-drinking beast) and īezzo (his blood, flowing through a person's veins).
Michel Launey, An Introduction to Classical Nahuatl, translated and adapted by Christopher MacKay (Cambridge: Cambridge University Press, 2011), 99.

With capes of various designs, the -yo ending refers to the design. e.g. axayacayo = cape with water-face design; tlachquauhyo tilmatli = cape with ball court design; tonatiuhyo tilmatli = cape with sun design.
Fray Bernardino de Sahagún, Primeros Memoriales, ed. Thelma D. Sullivan, et al. (Norman: University of Oklahoma Press, 1997), 204.

An abstract; can also mean "something that belongs, or is an inherent part, of something else; a noun with '-yotl' not possessed is merely a statement that something has that thing."
teotl = God, teoyotl = divinity
tecuio = lordship
nocal yhuan tlalmayo = my house and the level land that goes with it (tlalmantli + yotl)
Stephanie Wood and Robert Haskett's notes from seminars with James Lockhart.