Creating *.desktop files for WIndows/Wine applications, specify sometimes a Icon like this:

[Desktop Entry]
Name=Game to start
Comment=Play this game on Steam
Exec=steam steam://rungameid/738520
Icon=steam_icon_738520
Terminal=false
Type=Application
Categories=Game;

with Icon=steam_icon_738520. Is this extracted from the *.exe file and how do i get the name mentioned here? I know, that i can use the path to a *.png, but i would prefer to use the *.exe file itself.