+</PRE><H3><a name="h3-new_fieldtype">new_fieldtype</a></H3><PRE>
+ The function <B>new_fieldtype</B> creates a new field type usable for data
+ validation. Its parameters are function pointers:
+
+ <I>field</I><B>_</B><I>check</I>
+ This function checks the validity of an entered data string
+ whenever the user attempts to leave a field. It has two
+ arguments:
+
+ <B>o</B> The (FIELD *) argument is passed in so the validation
+ predicate can see the field's buffer, sizes and other
+ attributes.
+
+ <B>o</B> The second argument is an argument-block structure, about
+ which more below.
+
+ <I>char</I><B>_</B><I>check</I>
+ This function validates input characters as they are entered. The
+ form library passes it the character to be checked and a pointer
+ to an argument-block structure.
+
+
+</PRE><H3><a name="h3-free_fieldtype">free_fieldtype</a></H3><PRE>
+ The <B>free_fieldtype</B> function frees the space allocated for a given
+ validation type by <B>new_fieldtype</B>.
+
+
+</PRE><H3><a name="h3-set_fieldtype_arg">set_fieldtype_arg</a></H3><PRE>
+ The function <B>set_fieldtype_arg</B> associates three storage-management
+ functions with a field type:
+
+ <I>make</I><B>_</B><I>arg</I>
+ This function is automatically applied to the list of arguments
+ you give <B>set_field_type</B> when attaching validation to a field. It
+ stores the arguments in an allocated argument-block object which
+ is used when validating input.
+
+ <I>copy</I><B>_</B><I>arg</I>
+ This function may be used by applications to copy argument-blocks.
+
+ <I>free</I><B>_</B><I>arg</I>
+ Frees an argument-block structure.
+
+ You must supply the <I>make</I><B>_</B><I>arg</I> function. The other two are optional: you
+ may supply NULL for them. In this case, the form library assumes that
+ <I>make</I><B>_</B><I>arg</I> does not allocate memory but simply loads the argument into a
+ single scalar value.
+
+
+</PRE><H3><a name="h3-set_fieldtype_choice">set_fieldtype_choice</a></H3><PRE>
+ The form driver requests <B>REQ_NEXT_CHOICE</B> and <B>REQ_PREV_CHOICE</B> assume
+ that the possible values of a field form an ordered set, and provide
+ the forms user with a way to move through the set.
+
+ The <B>set_fieldtype_choice</B> function allows forms programmers to define
+ successor and predecessor functions for the field type. These
+ functions take the field pointer and an argument-block structure as
+ arguments.
+
+
+</PRE><H3><a name="h3-link_fieldtype">link_fieldtype</a></H3><PRE>
+ The function <B>link_fieldtype</B> creates a new field type from the two given
+ types. They are connected by an logical 'OR'.