system_data_types.7: Add 'uintmax_t'

Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

man7/system_data_types.7

@@ -1172,6 +1172,61 @@ See also:
 .BR getpwnam (2),
 .BR credentials (7)
 .RE
+.\"------------------------------------- uintmax_t --------------------/
+.TP
+.I uintmax_t
+.RS
+.br
+Include:
+.IR <stdint.h> .
+Alternatively,
+.IR <inttypes.h> .
+.PP
+An unsigned integer type
+capable of representing any value of any unsigned integer type
+supported by the implementation.
+According to the C language standard, it shall be
+capable of storing values in the range [0,
+.BR UINTMAX_MAX ].
+.PP
+The macro
+.B UINTMAX_C
+.\" TODO: Document UINT*_C(3)
+expands its argument to an integer constant of type
+.IR uintmax_t .
+.PP
+The length modifier for
+.I uintmax_t
+for the
+.BR printf (3)
+and the
+.BR scanf (3)
+families of functions is
+.BR j ;
+resulting commonly in
+.B %ju
+or
+.B %jx
+for printing
+.I uintmax_t
+values.
+.PP
+Bugs:
+.I uintmax_t
+is not large enough to represent values of type
+.I unsigned __int128
+in implementations where
+.I unsigned __int128
+is defined and
+.I unsigned long long
+is less than 128 bits wide.
+.PP
+Conforming to: C99 and later; POSIX.1-2001 and later.
+.PP
+See also the
+.I intmax_t
+type in this page.
+.RE
 .\"------------------------------------- va_list ----------------------/
 .TP
 .I va_list