+.SS EXTENDED NUMBER FORMAT
+.PP
+On occasion, 16-bit signed integers are not large enough.
+With \fBncurses\fP 6.1, a new format was introduced by making a few changes
+to the legacy format:
+.bP
+a different magic number (0542)
+.bP
+changing the type for the \fInumber\fP array from signed 16-bit integers
+to signed 32-bit integers.
+.PP
+To maintain compatibility, the library presents the same data structures
+to direct users of the \fBTERMTYPE\fP structure as in previous formats.
+However, that cannot provide callers with the extended numbers.
+The library uses a similar but hidden data structure \fBTERMTYPE2\fP
+to provide data for the terminfo functions.