-pan.

Headword: 
-pan.
Principal English Translation: 

in the time of; or a locative meaning on, at or in-place; over, on top of; with, by means of; for, in favor of; about (see Karttunen and Lockhart)

IPAspelling: 
-pɑn
Frances Karttunen: 

-PAN postposition on the surface of, for or at a particular time / dentro, sobre, en, durante, por (S) Z consistently has a long vowel, while there is agreement across other sources that the vowel is short.
Frances Karttunen, An Analytical Dictionary of Nahuatl (Norman: University of Oklahoma Press, 1992), 186.

Lockhart’s Nahuatl as Written: 

relational word. in, on, for, during, as, place of or among, etc.
-pan tlahtoa, to see to, take care of, be in charge of, sometimes to speak for.
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), 229.

Attestations from sources in English: 

in yquac cocoliztli inpan, ohuala? = when some sickness came upon them
Bartolomé de Alva, A Guide to Confession Large and Small in the Mexican Language, 1634, eds. Barry D. Sell and John Frederick Schwaller, with Lu Ann Homza (Norman: University of Oklahoma Press, 1999), 101.

Attestations from sources in Spanish: 

in yquac cocoliztli inpan, ohuala? = estando enfermos
Bartolomé de Alva, A Guide to Confession Large and Small in the Mexican Language, 1634, eds. Barry D. Sell and John Frederick Schwaller, with Lu Ann Homza (Norman: University of Oklahoma Press, 1999), 100–101.