This changed in 5.8.1 (from perlrun)

-C <number/list>

The -C flag controls some Unicode of the Perl Unicode features. <<Their typo not mine>>

~~snip~~

(In Perls earlier than 5.8.1 the -C switch was a Win32-only switch that enabled the use of Unicode-aware ``wide system call'' Win32 APIs. This feature was practically unused, however, and the command line switch was therefore ``recycled''.)

Thanks for pointing that out. The html docs on one machine must not have been updated properly, since it's Perl 5.8.2. (I noticed that Win32::API is missing from the index pane, even though the module is present, so this is the second anomoly today). On another machine, I see a different -C documentation.

Unicode characters can also be added to a string by using the \x{...} notation. The Unicode code for the desired character, in hexadecimal, should be placed in the braces. For instance, a smiley face is \x{263A}. This encoding scheme only works for characters with a code of 0x100 or above.

If at least one character in the string has a code of >= 0x100, then all characters >0x7F will be multi-byte encoded. If all the characters are less than 256, then it is also possible to encode the string with one byte per character. Some functions, like chr, make it a point to use the byte form when possible, since it's faster.