diff --git a/java/jsp-base-openapi/src/com/intellij/lang/jsp/JspFileViewProvider.java b/java/jsp-base-openapi/src/com/intellij/lang/jsp/JspFileViewProvider.java
index e926f53354a2..acad3c47338f 100644
--- a/java/jsp-base-openapi/src/com/intellij/lang/jsp/JspFileViewProvider.java
+++ b/java/jsp-base-openapi/src/com/intellij/lang/jsp/JspFileViewProvider.java
@@ -22,8 +22,5 @@ import java.util.Set;
  * @author ik
  */
 public interface JspFileViewProvider extends JspxFileViewProvider {
-
-  Set<String> getKnownTaglibPrefixes();
-
-  Set<String> getKnownTaglibPrefixes(CharSequence newContent);
+  Set<String> getXmlNsPrefixes(CharSequence buffer);
 }
diff --git a/xml/impl/src/com/intellij/codeInsight/editorActions/XmlTagNameSynchronizer.java b/xml/impl/src/com/intellij/codeInsight/editorActions/XmlTagNameSynchronizer.java
index b034cc5ffc8d..fbea7a3c3320 100644
--- a/xml/impl/src/com/intellij/codeInsight/editorActions/XmlTagNameSynchronizer.java
+++ b/xml/impl/src/com/intellij/codeInsight/editorActions/XmlTagNameSynchronizer.java
@@ -44,6 +44,7 @@ import com.intellij.psi.PsiDocumentManager;
 import com.intellij.psi.PsiElement;
 import com.intellij.psi.PsiFile;
 import com.intellij.util.SmartList;
+import com.intellij.xml.util.XmlUtil;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
 
@@ -200,7 +201,7 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
       }
 
       for (int i = 0; i < newLength; i++) {
-        if (!isValidTagNameChar(fragment.charAt(i))) {
+        if (!XmlUtil.isValidTagNameChar(fragment.charAt(i))) {
           clearMarkers();
           return;
         }
@@ -241,12 +242,12 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
           start = i + 1;
           break;
         }
-        if (!isValidTagNameChar(c)) break;
+        if (!XmlUtil.isValidTagNameChar(c)) break;
       }
       if (start < 0) return null;
       for (int i = offset; i < Math.min(document.getTextLength(), offset + 50); i++) {
         final char c = sequence.charAt(i);
-        if (!isValidTagNameChar(c)) {
+        if (!XmlUtil.isValidTagNameChar(c)) {
           end = i;
           break;
         }
@@ -255,10 +256,6 @@ public class XmlTagNameSynchronizer extends CommandAdapter implements Applicatio
       return document.createRangeMarker(start, end, true);
     }
 
-    private static boolean isValidTagNameChar(char c) {
-      return Character.isJavaIdentifierPart(c) || c == ':';
-    }
-
     public void beforeCommandFinished() {
       if (myMarkers.isEmpty()) return;
 
diff --git a/xml/xml-psi-impl/src/com/intellij/xml/util/XmlUtil.java b/xml/xml-psi-impl/src/com/intellij/xml/util/XmlUtil.java
index 94b06d4227c7..a21b283579c0 100644
--- a/xml/xml-psi-impl/src/com/intellij/xml/util/XmlUtil.java
+++ b/xml/xml-psi-impl/src/com/intellij/xml/util/XmlUtil.java
@@ -1345,6 +1345,11 @@ public class XmlUtil {
     return StringUtil.escapeXml(text);
   }
 
+  public static boolean isValidTagNameChar(char c) {
+    return Character.isLetter(c) || Character.isDigit(c) ||
+           c == ':' || c == '_' || c == '-' || c == '.';
+  }
+
   @Nullable
   public static String extractXmlEncodingFromProlog(@NotNull byte[] content) {
     return XmlCharsetDetector.extractXmlEncodingFromProlog(content);