-This writes the model to the file <code>filename</code>. The second parameter can return the total number of conversion failures (pass <code>NULL</code><code></code> if you're not interested).<br>
-<br>
-The functions in <a href="usage.html#Controlling_some_settings">this section</a> can be used before <code>gom_write_file</code> to control some settings.<br>
+This writes the model to the file <code>filename</code>. The second parameter can return the total number of conversion failures (pass <code>NULL</code><code></code> if you're not interested). The functions in <a href="usage.html#Controlling_some_settings">this section</a> can be used before <code>gom_write_file</code> to control some settings.<br>
+<br>
+Before you write the file, you can update the timestamp in the header using the following function:<br>
+<blockquote><code>int <b>gom_header_update_timestamp</b> (time_t tval);<br></code></blockquote>
+This sets the <code>date</code> and <code>time</code> fields of the header to the time indicated by <code>tval</code>.
+ The function returns 0 on success, non-zero if an error occurred. Typically,
+the function would be used as follows, to set the current time in the timestamp:<br>
+<blockquote><code>int result;<br>
+result = gom_header_update_timestamp(time(NULL));</code><br>
+</blockquote>