# What ist the fontspec equivalent for “variable=true”

With pdflatex, I used the cfr-lm package with following settings:

\usepackage[%
rm={oldstyle=false,proportional=true},%
sf={oldstyle=false,proportional=true},%
tt={oldstyle=false,proportional=true,variable=true},%
qt=false%
]{cfr-lm}


When using lualatex, I am using the following one

\setmainfont{Latin Modern Roman}
\setsansfont{Latin Modern Sans}
\setmonofont{Latin Modern Mono}


Now, each letter of the monospaced font has the same width. However, I like the variable=true feature. How can I active it at setmonofont?

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
! LaTeX error: "kernel/key-unknown"
!
! The key 'fontspec-opentype/Variable' is unknown and is being ignored.


As suggested by the table on page 8 of the cfr-lm documentation, what you’re looking for is Latin Modern Mono Prop, a set of fonts, not a feature of the better known Latin Modern Mono fonts. So you can use it this way:
\documentclass{article}