* 4~7 - reserved
  */
 enum {
-       EROFS_INODE_FLAT_PLAIN,
-       EROFS_INODE_FLAT_COMPRESSION_LEGACY,
-       EROFS_INODE_FLAT_INLINE,
-       EROFS_INODE_FLAT_COMPRESSION,
+       EROFS_INODE_FLAT_PLAIN                  = 0,
+       EROFS_INODE_FLAT_COMPRESSION_LEGACY     = 1,
+       EROFS_INODE_FLAT_INLINE                 = 2,
+       EROFS_INODE_FLAT_COMPRESSION            = 3,
        EROFS_INODE_LAYOUT_MAX
 };
 
 
 /* available compression algorithm types */
 enum {
-       Z_EROFS_COMPRESSION_LZ4,
+       Z_EROFS_COMPRESSION_LZ4 = 0,
        Z_EROFS_COMPRESSION_MAX
 };
 
  *                (di_advise could be 0, 1 or 2)
  */
 enum {
-       Z_EROFS_VLE_CLUSTER_TYPE_PLAIN,
-       Z_EROFS_VLE_CLUSTER_TYPE_HEAD,
-       Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD,
-       Z_EROFS_VLE_CLUSTER_TYPE_RESERVED,
+       Z_EROFS_VLE_CLUSTER_TYPE_PLAIN          = 0,
+       Z_EROFS_VLE_CLUSTER_TYPE_HEAD           = 1,
+       Z_EROFS_VLE_CLUSTER_TYPE_NONHEAD        = 2,
+       Z_EROFS_VLE_CLUSTER_TYPE_RESERVED       = 3,
        Z_EROFS_VLE_CLUSTER_TYPE_MAX
 };