From the footnotes:

"""Stablecoins that are purportedly convertible for an underlying fiat currency are distinct from a smaller subset of stablecoin arrangements that use other means to attempt to stabilize the price of the instrument (sometimes referred to as “synthetic” or “algorithmic” stablecoins) or are convertible for other assets. Because of their more widespread adoption, this discussion focuses on stablecoins that are convertible for fiat currency."""