Diacritical marks in flash
First, you have to make sure the font is inlined correctly, this can be easily tested by simply typing those very characters into the text box and if they show up for export, you should be good to go.
As far as reading a text file is concerned, it is somewhat more difficult, but not much. What you need to do is make sure the text file you are reading is in UTF8, any sane text editor should be able to save that (heck, even notepad does this now). You can force flash to respect the local character encoding, but this is very error prone and will likely break if someone with a different encoding looks at your application. So go for UTF8, flash pens with ease.
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To use them, you need to embed them in your application. The easiest way is to create a new TextField in your step, then insert these symbols under the properties bar (you will need to embed them for the specific font you are using). Just create your TextField out of sight and you should be good to go.
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