# Read from STDIN, and print each line out when it begins with 'i',
# or ends with either '/' or 'i'. Case insensitive.
print if (m|^|i || m||i);
As you can see, the code between the code tags is not faithfully reproduced, becuase the [i] and [/i] are being interpreted as markup, and not as part of the source code. This is clearly wrong behaviour.