[biblio] Brackets inside brackets

[Philipp Stephani]

2011/8/31 Pedro Costa <psdc1978 at gmail.com>:
>  In this example of a bibtex entry, the title fieldhas the value "{The
>  {X} Window System, Version 11}". Why X is between { }? What does it
>  means?

BibTeX usually de-titlecases title fields by replacing every
non-leading uppercase letter by its lowercase equivalent. So the title
"The X Window System, Version 11" would be converted to "The x window
system, version 11". The reasoning is that titles are often titlecased
in literature databases, but shouldn't be in the printed bibliography.
For words that are properly capitalized, this results in unwanted
lowercasing, as the example shows. BibTeX however doesn't lowercase
anything protected by an additional set of braces, therefore your
example gets converted to "The {X} window system, version 11". I think
even better would be to write "{The {X Windows System}..." because "X
Window System" is a proper noun.