diff --git a/gradle/publishing/publication.gradle b/gradle/publishing/publication.gradle
index c35fcb9..fd7d7b5 100644
--- a/gradle/publishing/publication.gradle
+++ b/gradle/publishing/publication.gradle
@@ -52,13 +52,14 @@ if (project.hasProperty("signing.keyId")) {
         sign publishing.publications.mavenJava
     }
 }
-
-nexusPublishing {
-    repositories {
-        sonatype {
-            username = project.property('ossrhUsername')
-            password = project.property('ossrhPassword')
-            packageGroup = "org.xbib"
+if (project.hasProperty("ossrhUsername")) {
+    nexusPublishing {
+        repositories {
+            sonatype {
+                username = project.property('ossrhUsername')
+                password = project.property('ossrhPassword')
+                packageGroup = "org.xbib"
+            }
         }
     }
 }
diff --git a/src/main/java/org/xbib/marc/MarcField.java b/src/main/java/org/xbib/marc/MarcField.java
index e5db143..acd20d0 100644
--- a/src/main/java/org/xbib/marc/MarcField.java
+++ b/src/main/java/org/xbib/marc/MarcField.java
@@ -18,9 +18,11 @@ package org.xbib.marc;
 import org.xbib.marc.dialects.mab.MabSubfieldControl;
 import org.xbib.marc.label.RecordLabel;
 
+import java.util.Arrays;
 import java.util.Collection;
 import java.util.Deque;
 import java.util.LinkedList;
+import java.util.List;
 import java.util.Map;
 import java.util.regex.Pattern;
 import java.util.stream.Collectors;
@@ -534,22 +536,30 @@ public class MarcField implements Comparable<MarcField> {
         }
 
         /**
-         * A key is a compact representation of tag/indicator/value
+         * A key is a compact representation of tag/indicator/value that are separated by a separator.
          * @param key the key as string
+         * @param separator the separator in the key
+         * @param value the value
          * @return this builder
          */
-        @SuppressWarnings("unchecked")
         public Builder key(String key, String separator, Object value) {
-            String[] s = key.split(separator);
-            switch (s.length) {
+            return key(Arrays.asList(key.split(separator)), value);
+        }
+
+        @SuppressWarnings("unchecked")
+        public Builder key(List<String> key, Object value) {
+            switch (key.size()) {
                 case 0: {
-                    // is that even possible?
-                    tag(key);
-                    value(value.toString());
+                    if (value instanceof Collection) {
+                        Collection<Map.Entry<String, Object>> collection = (Collection<Map.Entry<String, Object>>) value;
+                        for (Map.Entry<String, Object> entry : collection) {
+                            tag(entry.getKey()).value(entry.getValue().toString());
+                        }
+                    }
                     break;
                 }
                 case 1: {
-                    tag(s[0]);
+                    tag(key.get(0));
                     if (value instanceof Collection) {
                         Collection<Map.Entry<String, Object>> collection = (Collection<Map.Entry<String, Object>>) value;
                         for (Map.Entry<String, Object> entry : collection) {
@@ -561,8 +571,8 @@ public class MarcField implements Comparable<MarcField> {
                     break;
                 }
                 case 2: {
-                    tag(s[0]);
-                    String indicator = s[1].replace('_', ' ');
+                    tag(key.get(0));
+                    String indicator = key.get(1).replace('_', ' ');
                     if (indicator.isEmpty()) {
                         indicator(" ");
                     } else {
@@ -579,14 +589,14 @@ public class MarcField implements Comparable<MarcField> {
                     break;
                 }
                 case 3: {
-                    tag(s[0]);
-                    String indicator = s[1].replace('_', ' ');
+                    tag(key.get(0));
+                    String indicator = key.get(1).replace('_', ' ');
                     if (indicator.isEmpty()) {
                         indicator(" ");
                     } else {
                         indicator(indicator);
                     }
-                    String subfieldIds = s[2].replace('_', ' ');
+                    String subfieldIds = key.get(2).replace('_', ' ');
                     if (subfieldIds.isEmpty()) {
                         subfieldIds = " ";
                     }
@@ -601,7 +611,7 @@ public class MarcField implements Comparable<MarcField> {
                     break;
                 }
                 default:
-                    throw new IllegalArgumentException("key specification is invalid: " + key + " length = " + s.length);
+                    throw new IllegalArgumentException("key specification is invalid: " + key);
             }
             return this;
         }
diff --git a/src/main/java/org/xbib/marc/MarcRecord.java b/src/main/java/org/xbib/marc/MarcRecord.java
index 21bcb04..d588e0f 100644
--- a/src/main/java/org/xbib/marc/MarcRecord.java
+++ b/src/main/java/org/xbib/marc/MarcRecord.java
@@ -22,6 +22,7 @@ import static org.xbib.marc.json.MarcJsonWriter.TYPE_TAG;
 import org.xbib.marc.label.RecordLabel;
 
 import java.util.Collection;
+import java.util.Deque;
 import java.util.LinkedHashMap;
 import java.util.LinkedList;
 import java.util.List;
@@ -30,6 +31,8 @@ import java.util.Set;
 import java.util.TreeMap;
 import java.util.function.BiConsumer;
 import java.util.function.Predicate;
+import java.util.logging.Level;
+import java.util.logging.Logger;
 import java.util.regex.Pattern;
 
 /**
@@ -97,12 +100,12 @@ public class MarcRecord implements Map<String, Object> {
                                   String leaderTag,
                                   RecordLabel recordLabel) {
         MarcRecord marcRecord = new MarcRecord(map);
-        marcRecord.parseMap(map, ".", "", (key, value) ->
-            marcRecord.marcFields.add(MarcField.builder().key(key, "\\.", value).build()));
+        marcRecord.parseMap(map, "", new LinkedList<>(), (key, value) ->
+            marcRecord.marcFields.add(MarcField.builder().key(key, value).build()));
         if (map.containsKey(formatTag)) {
             marcRecord.format = map.get(formatTag).toString();
         }
-        if ( map.containsKey(typeTag)) {
+        if (map.containsKey(typeTag)) {
             marcRecord.type = map.get(typeTag).toString();
         }
         if (map.containsKey(leaderTag)) {
@@ -478,17 +481,21 @@ public class MarcRecord implements Map<String, Object> {
 
     @SuppressWarnings("unchecked")
     private void parseMap(Map<String, Object> source,
-                          String separator, String prefix,
-                          BiConsumer<String, Object> consumer) {
+                          String prefix,
+                          LinkedList<String> key,
+                          BiConsumer<List<String>, Object> consumer) {
+        if (!prefix.isEmpty()) {
+            key.addLast(prefix);
+        }
         List<Map.Entry<String, Object>> list = new LinkedList<>();
         source.forEach((k, v) -> {
             if (v instanceof Map) {
-                parseMap((Map<String, Object>) v, separator, prefix + k + separator, consumer);
+                parseMap((Map<String, Object>) v, k, key, consumer);
             } else if (v instanceof Collection) {
                 Collection<Object> collection = (Collection<Object>) v;
                 for (Object object : collection) {
                     if (object instanceof Map) {
-                        parseMap((Map<String, Object>) object, separator, prefix + k + separator, consumer);
+                        parseMap((Map<String, Object>) object, k, key, consumer);
                     } else {
                         list.add(Map.entry(k, object));
                     }
@@ -498,7 +505,10 @@ public class MarcRecord implements Map<String, Object> {
             }
         });
         if (!list.isEmpty()) {
-            consumer.accept(prefix, list);
+            consumer.accept(key, list);
+        }
+        if (!prefix.isEmpty()) {
+            key.removeLast();
         }
     }
 }