Use nbsp instead of ' ' to prevent word-wrap

sections/glossary.txt

@@ -70,7 +70,7 @@ the definitions for more information.
 	or more Unicode characters, such as a letter or symbol, or a set of letters.
 	In this specification, character values are denoted as a unicode string
 	(e.g., UNI{\u0020}) or a glyph representation of the same code point (e.g.,
-	GLYPH{ }), and are color coded to help distinguish these two representations.
+	GLYPH{ }), and are color coded to help distinguish these two representations.
 
 	<p class="note">
 	In source code, some key values, such as non-graphic characters, can be