+<br>
+<hr width="100%" size="2">
+<h2><a name="Other_functions"></a>Modifying the object model</h2>Currently, there are only functions available to modify strings in the model (and the date manipulation functions described <a href="interface.html#date_value">here</a>).
+ In principle it is possible to add new records, notes, ... yourself,
+but you have to know what you are doing, because you should keep the model
+consistent. In the next release, functions will be available to add,
+remove and modify anything in the model.<br>
+
+<h3><a name="Manipulating_strings"></a>Manipulating strings<br>
+</h3>
+There are some functions available to retrieve and change strings in the
+Gedcom object model, depending whether you use UTF-8 strings in your application
+or locale-defined strings.<br>
+<br>
+The following functions retrieve and set the string in UTF-8 encoding:<br>
+<blockquote><code>char* <b>gom_get_string</b> (char* data);<br>
+char* <b>gom_set_string</b> (char** data, const char* str_in_utf8);</code><br>
+</blockquote>
+The first function is in fact superfluous, because it just returns the <code>data</code>, but it is there for symmetry with the functions given below for the locale-defined input and output. <br>
+<br>
+The second function returns the new value if successful, or <code>NULL</code>
+if an error occurred (e.g. failure to allocate memory or the given string is not a valid UTF-8 string). It makes a
+copy of the input string to store it in the object model. It also takes
+care of deallocating the old value of the data if needed. Note that
+the set function needs the address of the data variable, to be able to modify
+it. In the case of an error, the target data variable is not modified.<br>
+<br>
+Examples of use of these strings would be, e.g. for retrieving and setting the system ID in the header:<br>
+<blockquote><code>struct header* head = gom_get_header();</code><code></code><br>
+ <code>char* oldvalue = gom_get_string(head->source.id);<br>
+char* newvalue = "My_Gedcom_Tool";<br>
+ </code><br>
+ <code>if (gom_set_string(&head->source.id, newvalue)) {<br>
+ printf("Modified system id from %s to %s\n", oldvalue, newvalue);<br>
+}</code><br>
+</blockquote>
+<br>
+A second couple of functions retrieve and set the string in the format defined by the current locale:<br>
+<blockquote><code>char* <b>gom_get_string_for_locale</b> (char* data, int* conversion_failures);<br>
+char* <b>gom_set_string_for_locale</b> (char** data, const char* str_in_locale)</code>;<br>
+</blockquote>
+The use of these functions is the same as the previous ones, but e.g. in
+the "en_US" locale the string will be returned by the first function in the
+ISO-8859-1 encoding and the second function expects the <code>str_in_locale</code> to be in this encoding. Conversion to and from UTF-8 for the object model is done on the fly.<br>
+<br>
+Since the conversion from UTF-8 to the locale encoding is not always possible,
+the get function has a second parameter that can return the number of conversion
+failures for the result string. Pass a pointer to an integer if you
+want to know this. You can pass <code>NULL</code> if you're not interested. The function returns <code>NULL</code>
+if an error occurred (e.g. if the given string is not a valid string for
+the current locale); in that case the target data variable is not modified.<br>
+<hr width="100%" size="2">
+<h2><a name="Writing_the_object_model_to_file"></a>Writing the object model to file<br>
+</h2>
+Writing the current object model to a file is simply done using the following function:<br>
+<blockquote><code>int <b>gom_write_file</b> (const char* filename, int* total_conv_fails);<br></code></blockquote>
+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>
+<hr width="100%" size="2"><br>
+