<FONT COLOR=red><A NAME="58_7">Typ</A></FONT> : <A HREF="terminal_interface-curses-forms-field_types-user__ads.htm#48_9">User_Defined_Field_Type</A>) <b>return</b> Boolean
<b>is</b> <b>abstract</b>;
<FONT COLOR=green><EM>-- If True is returned, the field is considered valid, otherwise it is</EM></FONT>
<FONT COLOR=red><A NAME="58_7">Typ</A></FONT> : <A HREF="terminal_interface-curses-forms-field_types-user__ads.htm#48_9">User_Defined_Field_Type</A>) <b>return</b> Boolean
<b>is</b> <b>abstract</b>;
<FONT COLOR=green><EM>-- If True is returned, the field is considered valid, otherwise it is</EM></FONT>