How to get rid of street type icons

I am generating the maps for my Etrex Vista HCx with mkgmap. On the Etrex, many streets have additional icons showing street type and numbers, like L502 or K83.

Does anyone know, how to make maps without these symbols?

Sometimes they are taking too much screen area and I really do not need them.

Edit the lines style file and delete or comment out the lines like:
highway=motorway {name ‘${ref|highway-symbol:hbox} ${name}’ | ‘${ref|highway-symbol:hbox}’ | ‘${name}’ }

The symbols are placed by that highway-symbol code.

Great! That is exactly what I was searching for. It works.