In article , jacob navia
writes:

I apologize for those problems but I can't help it. I am using an Apple
Macintosh system (OS X) and the whole system is Unicode. All software
including the mail client, text editor, web browser etc is all Unicode
(16 bits chars) and there is no way for me to see which characters
aren't ASCII since I haven't any software that doesn't accept
UTF8 (not even the vi editor!)

There are various ways to represent Unicode, UTF8 etc. A common one is
to have it correspond to ASCII if the characters in question are ASCII.
So, as long as you stick to ASCII characters, your post should show up
OK.

[Mod. note: for those people who don't know the ASCII character set, a
good rule is to avoid any accented characters, any non-Roman letters,
and any 'smart quotes'. Letters A-Z and a-z, numbers and basic
punctuation only, please. This is particularly important when cutting
and pasting from a web source. I'm posting this to make other people
aware of the issue -- mjh]

If you follow Martin's advice, things should be OK. Here is the ASCII
character set:

+------------------------------------------+
| 0 1 2 3 4 5 6 7 |
+---+--------------------------------------+
| 0 | NUL DLE SP 0 @ P ` p |
| 1 | SOH DC1 ! 1 A Q a q |
| 2 | STX DC2 " 2 B R b r |
| 3 | ETX DC3 # 3 C S c s |
| 4 | EOT DC4 $ 4 D T d t |
| 5 | ENQ NAK % 5 E U e u |
| 6 | ACK SYN & 6 F V f v |
| 7 | BEL ETB ' 7 G W g w |
| 8 | BS CAN ( 8 H X h x |
| 9 | HT EM ) 9 I Y i y |
| A | LF SUB * : J Z j z |
| B | VT ESC + ; K [ k { |
| C | FF FS , L \ l | |
| D | CR GS - = M ] m } |
| E | SO RS . N ^ n ~ |
| F | SI US / ? O _ o DEL |
+---+--------------------------------------+

The numbers at the top and at the side are combined to give the
hexadecimal number of the character. Thus, the "!" character has value
21 in hex, or 33 in decimal. Values 20 through 7E should be OK, i.e.
all but the first two columns and the DEL at the lower right. So,
anything which looks like something in the 6 rightmost columns should be
OK. (The first two columns and DEL are non-printable characters.)