Does not add an appendix(\appendix) in a book with the NCC-LATEX package

Question

I'm using MiKTeX 2.9, TeXnicCenter 2.02 (Compilation profile LaTeX => PDF). I'm trying to use the NCC-LATEX book class to create a book. I can not use the \appendix command. For example, the following code:

\documentclass[book
,a4paper
,14pt
,russian                                                                
,openright      
]{ncc}

\usepackage[T2A]{fontenc}                               
\usepackage[utf8]{inputenc}                         

\begin{document}    

\frontmatter                                                
\author{Автор}                                          
\title{Название}    
\maketitle                                                  
\tableofcontents                                        

\mainmatter                                                 
\chapter{глава}
Текст
\chapter{глава}
Текст
\chapter{глава}
Текст

\appendix                                                   
\chapter{Прил}
Текст приложения
\chapter{Прил}
Текст приложения

\end{document}

compiles with an error (standard class book this example normally compiles):

! Undefined control sequence.
\@Alph #1->\text {\cyr \@Asbuk
                               {#1}}
l.67 \chapter{Прил}
The control sequence at the end of the top line
of your error message was never \def'ed. If you have
misspelled it (e.g., `\hobx'), type `I' and the correct
spelling (e.g., `I\hbox'). Otherwise just continue,
and I'll forget about whatever was undefined. 

! Missing number, treated as zero.
<to be read again>
                   }
l.67 \chapter{Прил}   
A number should have been here; I inserted `0'.
(If you can't figure out why I needed to see a number,
look up `weird error' in the index to The TeXbook.)

I do not want to use other classes. The author of the NCC class adapted it for Russian imposition standards.

It seems to me that LaTeX does not like Russian letters in appendix numbering, but I do not know what to do with it.

Answer 1

You can try this:

\documentclass[book
,a4paper
,14pt
,russian
,openright
]{ncc}

\usepackage[T2A]{fontenc}
\usepackage[utf8]{inputenc}
\makeatletter
\let \@Asbuk\russian@Alph
\let \@asbuk\russian@alph
\makeatother
\begin{document}
\frontmatter
\author{Автор}
\title{Название}
\maketitle
\tableofcontents

\mainmatter
\chapter{глава}
Текст
\chapter{глава}
Текст
\chapter{глава}
Текст

\appendix 
\chapter{Прил}
Текст приложения
\chapter{Прил}
Текст приложения

\end{document}