+ /* new hghmsg is hghmsg + numburst
+ *
+ * At this point, there is an array of numburst smsgs, each element of
+ * which contains the starting and stopping offsets (seeks) of the message
+ * in the digest. The inplace flag is set if the original digest is replaced
+ * by a message containing the table of contents. smsgs[0] is that table of
+ * contents. Go through the message numbers in reverse order (high to low).
+ *
+ * Set f1 to the name of the destination message, f2 to the name of a scratch
+ * file. Extract a message from the digest to the scratch file. Move the
+ * original message to a backup file if the destination message number is the
+ * same as the number of the original message, which only happens if the
+ * inplace flag is set. Then move the scratch file to the destination message.
+ *
+ * Moving the original message to the backup file is equivalent to deleting the
+ * message from the point of view of the external hooks. And bursting each
+ * message is equivalent to adding a new message.
+ */
+