Standard method for showing changes made to a LaTeX manuscript I am about to resubmit a manuscript to a journal, having now addressed the reviewers' feedback.

The instructions say to submit my final manuscript along with a "marked-up manuscript", which is "the final version showing all changes from the former version".

Since my manuscript is in LaTeX, what is the standard way of highlighting the changes I made?  Had it been a Microsoft Word document, I would have used the "track changes" feature.  More so than technical methods, I am wondering what format the reviewers typically expect. Are they asking for a marked-up, compiled PDF? Or a marked-up TeX source code? Or a side-by-side comparison of the source code?
When submitting to IEEE journals which require to highlight the changes, I simply colour them in red (no one complained so far...).

\usepackage{xcolor}   
\newcommand{\rev}[1]{{\color{red} #1}} 
%
%...
%
\rev{Hey, I'm a change}


For purpose of reviewing, they just need a compiled PDF. For the final submission, you can simply redefine the \rev command to do nothing.