I am bound to an infinitely wide command line.
I have one line of text that my user will likely spend hours analysing for whatever reason. It is important that they can tell very easily and very quickly how many characters in from the start they are.
The stock standard way of doing this is writing out
on the line below. This is all well and good for up to maybe 40 characters. One could put markers down on the third line every 25 characters noting the multiple of 25 making this valid for far longer strings.
The rest is up to you to work out. You can do better than '123...' or '^n*25'. Remember, this is an infinitely wide cmd-style console not a web page so there is no way of showing popups when the user mouses over something.