Ignore my previous question. In fact my previous test files where created manually, but with the wrong position for the ROL override. It works with this sample:
<html> <head><title>Test BiDi overrides</title></head><body> <div style="margin:1px 1px;border:1px solid blue;width:300px;padding:1px 1px;"> <p style="font-family: sans-serif;">Latin &rlo;test1&pdf; test2</p> <bdo dir="rtl"><p style="font-family: sans-serif;">Latin &rlo;test3&pdf; test4</p></bdo> <bdo dir="ltr"><p style="font-family: sans-serif;">Latin &rlo;test5&pdf; test6</p></bdo> <p style="font-family: 'JG Mende';">PUAs &rlo;test1:  &pdf; test2: </p> <bdo dir="rtl"><p style="font-family: 'JG Mende';">PUAs &rlo;test3:  &pdf; test4: </p></bdo> <bdo dir="ltr"><p style="font-family: 'JG Mende';">PUAs &rlo;test5:  &pdf; test6: </p></bdo> </div></body></html> Here I prefered using &rlo; and &pdf; in HTML but for plain-text or older browsers, it would probably be better to use the numeric codepoints of these controls (and care of their placement in a plain-text document, something I forgot to check...).
