+O_VISIBLE
+The field is displayed.
+If this option is off, display of the field is
+suppressed.
+.TP 5
+O_WRAP
+Words that do not fit on a line are wrapped to the next line.
+Words are
+blank-separated.
+.PP
+These extension options are defined (extensions are off by default):
+.TP 5
+O_DYNAMIC_JUSTIFY
+Permit dynamic fields to be justified, like static fields.
+.TP 5
+O_NO_LEFT_STRIP
+Preserve leading whitespace in the field buffer, which is normally discarded.
+.TP 5
+O_EDGE_INSERT_STAY
+When inserting into a field up to the boundary position,
+optionally delay the scrolling,
+so that the last inserted character remains visible,
+but advance the cursor to reflect the insertion.
+This allows the form library to display the
+inserted character in one-character fields
+as well as allowing the library to maintain consistent state.
+.TP 5
+O_INPUT_FIELD
+The \fBset_max_field\fP function checks for this extension,
+which allows a dynamic field to shrink if the new
+limit is smaller than the current field size.