ArthurZ,
Opening a file in the Read-Only mode insure that you will not change it occasionally. In this mode the Editor works as a Viewer while preserving all highlights, tags and other settings.
A possibility to pass a Read-Only flag/switch/parameter from a command line is also might be very useful since it allows opening the files in the Viewer(Read-Only) mode automatically by just passing a file name to the script.
Thank you!