Identify areas of text to be marked with changebars with the
\cbstart and \cbend commands; the bars may be coloured. The
package uses 'drivers' to place the bars; the available drivers
can work with dvitoln03, dvitops, dvips, the emTeX and TeXtures
DVI drivers, and VTeX and pdfTeX.

Homepage:
https://ctan.org/pkg/changebar
