-</PRE>
-<H3><a name="h3-Mouse-handling">Mouse handling</a></H3><PRE>
- If the second argument is the KEY_MOUSE special key, the
- associated mouse event is translated into one of the above
- pre-defined requests. Currently only clicks in the user
- window (e.g., inside the form display area or the decora-
- tion window) are handled.
+</PRE><H3><a name="h3-Field-validation">Field validation</a></H3><PRE>
+ The form library makes updates to the window associated with form
+ fields rather than directly to the field buffers.
+
+ The form driver provides low-level control over updates to the form
+ fields. The form driver also provides for validating modified fields
+ to ensure that the contents meet whatever constraints an application
+ may attach using <STRONG>set_field_type</STRONG>.
+
+ You can validate a field without making any changes to it using
+ <STRONG>REQ_VALIDATION</STRONG>. The form driver also validates a field in these cases:
+
+ <STRONG>o</STRONG> a call to <STRONG>set_current_field</STRONG> attempts to move to a different field.
+
+ <STRONG>o</STRONG> a call to <STRONG>set_current_page</STRONG> attempts to move to a different page of
+ the form.
+
+ <STRONG>o</STRONG> a request attempts to move to a different field.
+
+ <STRONG>o</STRONG> a request attempts to move to a different page of the form.
+
+ In each case, the move fails if the field is invalid.
+
+ If the modified field is valid, the form driver copies the modified
+ data from the window associated with the field to the field buffer.
+
+
+</PRE><H3><a name="h3-Mouse-handling">Mouse handling</a></H3><PRE>
+ If the second argument is the KEY_MOUSE special key, the associated
+ mouse event is translated into one of the above pre-defined requests.
+ Currently only clicks in the user window (e.g., inside the form display
+ area or the decoration window) are handled.