  During the last few decades, the most widely favored models for coronal
heating have involved the in situ dissipation of energy, with footpoint
shuffling giving rise to multiple current sheets (the "nanoflare" model) or to
Alfv{\'e}n waves that leak into the corona and undergo dissipative interactions
(the wave heating scenario). As has been recognized earlier, observations
suggest instead that the energy deposition is concentrated at very low heights,
with the coronal loops being filled with hot, dense material from below, which
accounts for their overdensities and flat temperature profiles. While an
obvious mechanism for footpoint heating would be reconnection with small-scale
fields, this possibility seems to have been widely ignored because magnetograms
show almost no minority-polarity flux inside active region (AR) plages. Here,
we present further examples to support our earlier conclusions (1) that
magnetograms greatly underrepresent the amount of minority-polarity flux inside
plages and "unipolar" network, and (2) that small loops are a major constituent
of \ion{Fe}{9} 17.1 nm moss. On the assumption that the emergence or churning
rate of small-scale flux is the same inside plages as in mixed-polarity regions
of the quiet Sun, we estimate the energy flux density associated with
reconnection with the plage fields to be on the order of 10$^7$ erg cm$^{-2}$
s$^{-1}$, sufficient to heat the AR corona.
