I'm not sure whether help can be found here, but maybe anyone has an idea? I edit letters with XeTeX and many originals of the letters have holes punched with a perforator. It is usually easy to reconstruct the right reading but I need a simple and inoffensive way to mark the text. I can't do grey letters, because I use that for uncertain readings. I don't want to do brackets as that would be too visi[b]le. I can't do underline as I already have that in the text. I thought of making a grey line like a strikethrough only behind not in front of the letters. To achieve that I played around with a framebox with little extension but that seems to be in front of the letters as well. Does something come to mind?
I decided to go with a gray underlining. The tikz-solution works because it is possible to combine a bolder gray line with a thin black underline, so I actually can combine both. Another advantage is, that the tikz-underlining allows line break within strike out and underlining. I basically could use the code posted by Peter Grill here:
The only disadvantage is that tikz needs several runs.