Version 0.21 of this package was accepted for publication in volume 10 of the journal The Journal of Software for Algebra and Geometry on 5 December 2019, in the article Seminormalization package for Macaulay2. That version can be obtained from the journal or from the Macaulay2 source code repository, http://github.com/Macaulay2/M2/blob/master/M2/Macaulay2/packages/Seminormalization.m2, commit number 7a7e6f96b0122482f5d60306f34d06fd8ae1e885.
This documentation describes version 0.21 of Seminormalization.
The source code from which this documentation is derived is in the file Seminormalization.m2.