commit 37d8ae25e1d899170c6e680923280626b7d9d4b3
Author: Tanmai Khanna <khanna.tanmai@gmail.com>
Date:   Sun Jun 14 22:12:42 2020 +0530

    dtd file works | fix arx file to be valid

diff --git a/samples/apertium-eng-spa.spa-eng.arx b/samples/apertium-eng-spa.spa-eng.arx
index 38f4671..82c3edb 100644
--- a/samples/apertium-eng-spa.spa-eng.arx
+++ b/samples/apertium-eng-spa.spa-eng.arx
@@ -70,6 +70,18 @@
     	<def-cat n="cop">
     		<cat-item has-tags="cop"/>
     	</def-cat>
+      
+      <def-cat n="adv">
+        <cat-item has-tags="adv"/>
+      </def-cat>
+      
+      <def-cat n="preadv">
+        <cat-item has-tags="preadv"/>
+      </def-cat>
+      
+      <def-cat n="predet">
+        <cat-item has-tags="predet"/>
+      </def-cat>
 
 	</section-def-cats>
 
diff --git a/src/anaphora.dtd b/src/anaphora.dtd
index 6717aa3..e928f63 100644
--- a/src/anaphora.dtd
+++ b/src/anaphora.dtd
@@ -85,7 +85,8 @@
 -->
 
 <!ELEMENT pattern-item EMPTY>
-<!ATTLIST pattern-item n IDREF #REQUIRED>
+<!ATTLIST pattern-item n IDREF #REQUIRED
+                       head CDATA #IMPLIED>
 <!--
     Each attribute to be activated is referred to by its name in the def-cats section
 -->