In this article, we introduce the space of formal power series of class $\mathbb M$ of Roumieu (resp., Beurling) type, which is the generalization of the space of entire functions of normal (resp., minimal) type with respect to a proximate order. And we characterize continuous endomorphisms of these spaces.
Dedicate to Professor R. Ishimura
"The spaces of formal power series of class M of Roumieu type and of Beurling type." Hiroshima Math. J. 50 (1) 117 - 135, March 2020. https://doi.org/10.32917/hmj/1583805652