If you mean reading the contents of for example a txt file, you can do:
var myFile = File.openDialog("Choose the file to open for reading");
var myResult = myFile.open("r", undefined, undefined);
If you mean open an Indesign document as read only, I guess you should save as template.
Thomas B. Nielsen
Thank you Thomas,
you are right. I was meaning open an InDesign document as read only. Saving the document as a template is not an option in my case (we use the indesign lock files to control what the user can do). I thought that perhaps there would be an easy way to do it, an "openRO()" function or something like that :-). It doesn´t matter, I will do it programmatically.