Add preliminary support for split into annual volumes
and drop support for not splitting
e.g. `make test YY=18`
does not yet work for the index
diff --git a/xslt/epub2i5.xsl b/xslt/epub2i5.xsl
index e737f5b..fad5d88 100644
--- a/xslt/epub2i5.xsl
+++ b/xslt/epub2i5.xsl
@@ -162,7 +162,7 @@
<!-- END variables derived from sru request to dnb archive -->
- <xsl:variable name="corpus_sigle" select="'DNB'"/>
+ <xsl:variable name="corpus_sigle" select="concat('DNB', substring($erscheinungsjahr, 3, 2))"/>
<!-- for BOTD: -->
<!-- Dokumentsigle muss zusammen mit Korpussigle (z.B DIV fuer loz-div und loz-div-pub) eindeutig sein -->