We prove that a Prufer domain R has an m-canonical ideal I, that is, a
n ideal I such that I : (I : J) = J for every ideal J of R, if and onl
y if R is h-local with only finitely many maximal ideals that are not
finitely generated; moreover, if these conditions are satisfied, then
the product of the non-finitely generated maximal ideals is an m-canon
ical ideal of R.