What to call the phenomenon where a rectangle is shown because a font is missing a glyph


Is there a name to describe the situation where a particular
[character](http://en.wiktionary.org/wiki/character) is shown on a computer
screen in a particular [font](http://en.wiktionary.org/wiki/font#Noun_2), but
this font does not have a [glyph](http://en.wiktionary.org/wiki/glyph) for
this particular character?

Usually, the result looks like this: □  
A kind of empty rectangle. Sometimes it shows the code for that character
within the rectangle.

![tofubake](https://i.stack.imgur.com/jyyEl.png)

How do yo call this phenomenon in Japanese?  
If there is no name, is there a common term referring to this "missing glyph
square" in Japanese?

_(It is not[文字化け](http://en.wiktionary.org/wiki/mojibake). 文字化け happens when
[character encoding](http://en.wiktionary.org/wiki/character_encoding) meta-
information is lost. It is not the problem here. Using a better font solves
this phenomenon, but does not solve 文字化け. Selecting a character encoding
solves 文字化け, but does not solve this phenomenon.)_




As far as Internet slang goes, the word
[豆腐{とうふ}](http://ja.wikipedia.org/wiki/%E8%B1%86%E8%85%90) is often used as a
term for replacement glyphs because of their rectangular shapes, and 豆腐[化]{ば}け
or 豆腐[化]{か} describe the phenomenon in one word.

>   * 画面上の日本語がすべて豆腐になってしまっていて読めない
>   * フォント設定を変更しても豆腐化けが直らない
>




As far as Internet slang goes, the word
[豆腐{とうふ}](http://ja.wikipedia.org/wiki/%E8%B1%86%E8%85%90) is often used as a
term for replacement glyphs because of their rectangular shapes, and 豆腐[化]{ば}け
or 豆腐[化]{か} describe the phenomenon in one word.

>   * 画面上の日本語がすべて豆腐になってしまっていて読めない
>   * フォント設定を変更しても豆腐化けが直らない
>

