My personal experience of the most common problematic substitutions by tools such as Outlook, Word & some web tools:
1. Double Quotes \u201c & \u201d “”
2. Single Quotes \u2018 & \u2019 ‘’
3. The m-hyphen \2013 –
4. Copyright © \xa9 and others, Registered ® \xae and trademark ™ \u2122
5. Some fractions e.g. ½ ¼
6. Non-breaking spaces
From: David Mertz
6. Change the error message "SyntaxError: invalid character in identifier" to include which character and it's Unicode value so that it becomes "SyntaxError: invalid character 0x201c " in identifier" - More informative error messages are good :-)
I wouldn't mind messages that actually looked specifically for some of those common annoying auto-substitutions. E.g.: % python ~/tmp/wrongchar.py File "/home/dmertz/tmp/wrongchar.py", line 1 x = 2014 – 2013 ^ SyntaxError: invalid character in identifier The hyphen really does look a lot like the n-dash that is on screen. And I think that's one of those substitutions that word processors and email clients often do. Maybe a collection of the top 20 such common substitutions with some fitting message. I dunno "SyntaxError: invalid character U+2013 may be substitution of ASCII dash". -- The dead increasingly dominate and strangle both the living and the not-yet born. Vampiric capital and undead corporate persons abuse the lives and control the thoughts of homo faber. Ideas, once born, become abortifacients against new conceptions.