Appendices labelled with numbers?

[Joachim Ziegler <ziegler@mpi-sb.mpg.de>]

Hello list,

I recently switched to docbook-xsl-1.69.0.

Now I discovered that my appendices are labeled with 1,2,3,... instead
of A,B,C,...

I did not change anything in my customization layer.

How can I get the letters back?

Thank you,
Joachim