diff --git a/configure.ac b/configure.ac
index f586cd1..9af99d0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1,4 +1,4 @@
-AC_INIT([libisofs], [0.6.6], [http://libburnia-project.org])
+AC_INIT([libisofs], [0.6.7], [http://libburnia-project.org])
 AC_PREREQ([2.50])
 dnl AC_CONFIG_HEADER([config.h])	
 
@@ -44,7 +44,7 @@ dnl If LIBISOFS_*_VERSION changes, be sure to change AC_INIT above to match.
 dnl
 LIBISOFS_MAJOR_VERSION=0
 LIBISOFS_MINOR_VERSION=6
-LIBISOFS_MICRO_VERSION=6
+LIBISOFS_MICRO_VERSION=7
 LIBISOFS_VERSION=$LIBISOFS_MAJOR_VERSION.$LIBISOFS_MINOR_VERSION.$LIBISOFS_MICRO_VERSION
 
 AC_SUBST(LIBISOFS_MAJOR_VERSION)
@@ -54,10 +54,10 @@ AC_SUBST(LIBISOFS_VERSION)
 
 dnl Libtool versioning
 LT_RELEASE=$LIBISOFS_MAJOR_VERSION.$LIBISOFS_MINOR_VERSION
-# SONAME = 6 - 0 = 6 . Library name = libisofs.6.0.0
-LT_CURRENT=7
+# SONAME = 8 - 2 = 6 . Library name = libisofs.6.2.0
+LT_CURRENT=8
 LT_REVISION=0
-LT_AGE=1
+LT_AGE=2
 LT_CURRENT_MINUS_AGE=`expr $LT_CURRENT - $LT_AGE`
 
 AC_SUBST(LT_RELEASE)
diff --git a/libisofs/libisofs.h b/libisofs/libisofs.h
index 891925a..4a40923 100644
--- a/libisofs/libisofs.h
+++ b/libisofs/libisofs.h
@@ -280,7 +280,11 @@ struct iso_data_source
      *     Buffer where the data will be written. It should have at least
      *     2048 bytes.
      * @return
-     *      1 if success, < 0 on error (has to be a valid libisofs error code)
+     *      1 if success,
+     *    < 0 if error. This function has to emit a valid libisofs error code.
+     *        Predifined (but not mandatory) for this purpose are:
+     *          ISO_DATA_SOURCE_SORRY ,   ISO_DATA_SOURCE_MISHAP,
+     *          ISO_DATA_SOURCE_FAILURE , ISO_DATA_SOURCE_FATAL
      */
     int (*read_block)(IsoDataSource *src, uint32_t lba, uint8_t *buffer);
 
@@ -867,7 +871,7 @@ int iso_lib_is_compatible(int major, int minor, int micro);
  */
 #define iso_lib_header_version_major  0
 #define iso_lib_header_version_minor  6
-#define iso_lib_header_version_micro  6
+#define iso_lib_header_version_micro  7
 
 /**
  * Usage discussion:
@@ -3900,4 +3904,16 @@ void iso_stream_get_id(IsoStream *stream, unsigned int *fs_id, dev_t *dev_id,
 /** El-Torito image is hidden (WARNING,HIGH, -335) */
 #define ISO_EL_TORITO_HIDDEN            0xD030FEB1
 
+/** Read error occured with IsoDataSource (SORRY,HIGH, -513) */
+#define ISO_DATA_SOURCE_SORRY     0xE030FCFF
+
+/** Read error occured with IsoDataSource (MISHAP,HIGH, -513) */
+#define ISO_DATA_SOURCE_MISHAP    0xE430FCFF
+
+/** Read error occured with IsoDataSource (FAILURE,HIGH, -513) */
+#define ISO_DATA_SOURCE_FAILURE   0xE830FCFF
+
+/** Read error occured with IsoDataSource (FATAL,HIGH, -513) */
+#define ISO_DATA_SOURCE_FATAL     0xF030FCFF
+
 #endif /*LIBISO_LIBISOFS_H_*/
diff --git a/libisofs/messages.c b/libisofs/messages.c
index cd68ca6..78b4f9a 100644
--- a/libisofs/messages.c
+++ b/libisofs/messages.c
@@ -204,6 +204,11 @@ const char *iso_error_to_msg(int errcode)
         return "Image write cancelled";
     case ISO_EL_TORITO_HIDDEN:
         return "El-Torito image is hidden";
+    case ISO_DATA_SOURCE_SORRY:
+    case ISO_DATA_SOURCE_MISHAP:
+    case ISO_DATA_SOURCE_FAILURE:
+    case ISO_DATA_SOURCE_FATAL:
+        return "Read error occured with IsoDataSource";
     default:
         return "Unknown error";
     }