Rendering software which cannot process a Unicode character appropriately often displays it as an open rectangle, or the Unicode "replacement character" (U+FFFD, �), to indicate the position of the unrecognized character. Some systems have made attempts to provide more information about such characters. The Apple's Last Resort font will display a substitute glyph indicating the Unicode range of the character, and the SIL International's Unicode Fallback font will display a box showing the hexadecimal scalar value of the character.
What does rendering software display when it can't process a Unicode character?  What is the code for the Unicode replacement character?  What is the name of Apple's font?  What company uses the Unicode Fallback font?  What does SIL's Unicode Fallback font display when it can't display a character properly? 