This is a package for handling multi-projective varieties, that is, closed subvarieties of products of projective spaces, and rational maps between them. This extends the package Cremona, which treats rational maps from multi-projective varieties to standard projective varieties, $X\subseteq \mathbb{P}^{k_1}\times\mathbb{P}^{k_2}\times\cdots\times\mathbb{P}^{k_n}\dashrightarrow Y\subseteq\mathbb{P}^N$.
Version 2.3 of this package was accepted for publication in volume 11 of The Journal of Software for Algebra and Geometry on 31 August 2021, in the article Computations with rational maps between multi-projective varieties (DOI: 10.2140/jsag.2021.11.143). That version can be obtained from the journal or from the Macaulay2 source code repository.
This documentation describes version 2.7.1 of MultiprojectiveVarieties.
The source code from which this documentation is derived is in the file MultiprojectiveVarieties.m2.
The object MultiprojectiveVarieties is a package.