+\begin_layout Subsubsection
+
+\lang english
+Availability
+\end_layout
+
+\begin_layout Standard
+
+\lang english
+New users are sometimes puzzled by the fact that many of the document classes
+ listed under
+\family sans
+Document\SpecialChar \menuseparator
+Settings\SpecialChar \menuseparator
+Document Class
+\family default
+\lang spanish
+
+\begin_inset Index idx
+status collapsed
+
+\begin_layout Plain Layout
+Documentos ! Configuración
+\end_layout
+
+\end_inset
+
+
+\lang english
+ are marked as
+\begin_inset Quotes eld
+\end_inset
+
+Unavailable
+\begin_inset Quotes erd
+\end_inset
+
+.
+ Or they are surprised that, when they open e.
+\begin_inset space \thinspace{}
+\end_inset
+
+g.
+\begin_inset space ~
+\end_inset
+
+the
+\family sans
+iop-article
+\family default
+ template, they receive a warning saying that the document requires files
+ that are not installed to produce output.
+ So it seems that something is wrong.
+\end_layout
+
+\begin_layout Standard
+
+\lang english
+But nothing is wrong.
+ LyX includes many more document classes than you will ever need to use,
+ and some of them, like
+\family sans
+IOP
+\family default
+, are highly specialized.LyX tries to support as many different types of
+ documents as possible, and it includes almost one hundred different layout
+ files, with a growing number.
+ No LaTeX distribution will install by default all files that might be needed
+ by some document class.
+ There are just too many of them.
+ That is why some of the document classes are unavailable.
+\end_layout
+
+\begin_layout Standard
+
+\lang english
+If there is a document class you would like to use that is marked as `Unavailabl
+e', you need to install the appropriate package files.
+ The easiest way to find out which files you need to install is to use that
+ document class for a new file.
+ LyX will display a dialog that will list the missing files.
+ See section
+\begin_inset Quotes eld
+\end_inset
+
+Installing new LaTeX files
+\begin_inset Quotes erd
+\end_inset
+
+ of the
+\emph on
+Customization
+\emph default
+ manual for information on how to install them.
+\begin_inset VSpace medskip
+\end_inset
+
+
+\end_layout
+
+\begin_layout Standard
+
+\lang english
+Although LyX provides support for many different sorts of documents, it
+ does not include support for every document class people might want to
+ use.
+ For example, many universities provide LaTeX class files to be used for
+ dissertations submitted to those universities.
+ The LyX team cannot write layout files to support every one of these.
+ There are too many.
+ Fortunately, users can write their own layout files, and many users have
+ done so.
+ Chapter
+\begin_inset space ~
+\end_inset
+
+5 of the
+\emph on
+Customization
+\emph default
+ manual contains information on how to create layout files.
+\end_layout
+