What input voltages does the 85W Magsafe 2 power adapter accept?
"Input: 100-240V~ 1.5A 50-60 Hz Output:20V [DC] 4.25A max"

The answer is in fact on the side of the adapter. There is text on the plug end and on one of the narrow sides of the adapter. The input information is on the narrow side, in low-contrast light-grey fine print on a white background (thank you, Apple). With a light and a magnifier, my old eyes were finally able to make it out.

"[DC]" refers to a symbol with a solid line next to a dashed line, meaning "direct current".