Mixing R-L and L-R scripts (as has been discussed here on many occasions) is a ripe arena for mysterious behavior. Given that even monolingual texts in R-L scripts will often include L-R characters, it can get hairy quickly. A desire to try to avoid having visible markers in text around the transitions is partly why the Unicode spec around bidi text is so complicated.
If you are using plain text and don't have access to HTML or CSS markup, you can follow the RTL character with U+200E LEFT-TO-RIGHT MARK to achieve the same effect. And even if you do have access to those things, using U+200E ensures that operations that strip markup (like copy-paste) don't break your text.
A fun hack I remember was that Windows internally used two left-to-right control characters in a window title as an indicator that the entire window should have its content flipped right to left, images and all (imagine a clock animation running counter-clockwise).
This meant that if you could control the window title somehow you could create some surprising behavior, such as putting both those characters at the beginning of a post on a web forum and then having both the web page and browser look backward after someone opened the link.
I believe most things filter for this now, of course.
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[ 3.2 ms ] story [ 27.5 ms ] threadThis meant that if you could control the window title somehow you could create some surprising behavior, such as putting both those characters at the beginning of a post on a web forum and then having both the web page and browser look backward after someone opened the link.
I believe most things filter for this now, of course.