The original author of this package is Kim C. Border (+ 2020-11-19)

The TeX command \bordermatrix is used to create a matrix with 
labeled rows and columns. Its syntax resembles traditional Plain TeX 
and does not use \begin{} and \end{} environments. Here is a simple 
example of its standard usage: 
\bordermatrix{ & c_1 & c_2 \cr r_1 & a_{11} & a_{12} \cr r_2 & a_{21} & a_{22} } 
Individual rows are terminated with \cr. Note that \bordermatrix places parentheses 
around the main body of the matrix by default.

Package kbordermatrix provides a command of the same name which uses by default
square brackets and the LaTeX syntax for tabular lines and columns. The first
column and line of the matrix are defined as labels with an decreased fontsize.

This file is distributed under the terms of the LaTeX Project Public
License from CTAN archives in directory  macros/latex/base/lppl.txt.
Either version 1.3 or, at your option, any later version.

hvoss@tug.org