# term 5

    term(5)                                                                term(5)

## NAME

           term - format of compiled term file.

## SYNOPSIS

           term

## DESCRIPTION

### STORAGE LOCATION

           Compiled   terminfo   descriptions   are  placed  under  the  directory
           /usr/local/ncurses/lib/terminfo.   Two  configurations  are   supported
           (when building the ncurses libraries):

           directory tree
                A two-level scheme is used to avoid a linear search of a huge UNIX
                system  directory:  /usr/local/ncurses/lib/terminfo/c/name   where
                name  is the name of the terminal, and c is the first character of
                name.     Thus,    act4    can    be    found    in    the    file
                /usr/local/ncurses/lib/terminfo/a/act4.   Synonyms  for  the  same
                terminal are implemented by multiple links to  the  same  compiled
                file.

           hashed database
                Using Berkeley database, two types of records are stored: the ter-
                minfo data in the same format as stored in a directory  tree  with
                the  terminfo's primary name as a key, and records containing only
                aliases pointing to the primary name.

                If built to write hashed databases, ncurses can  still  read  ter-
                minfo  databases  organized  as a directory tree, but cannot write
                entries into the  directory  tree.   It  can  write  (or  rewrite)
                entries in the hashed database.

                ncurses  distinguishes  the  two  cases  in  the TERMINFO and TER-
                MINFO_DIRS environment variable by assuming a directory  tree  for
                entries that correspond to an existing directory, and hashed data-
                base otherwise.

### LEGACY STORAGE FORMAT

           The format has been chosen so that it will be the same on all hardware.
           An  8 or more bit byte is assumed, but no assumptions about byte order-
           ing or sign extension are made.

           The compiled file is created with the tic program, and read by the rou-
           tine  setupterm(3x).   The  file is divided into six parts: the header,
           terminal names, boolean flags, numbers, strings, and string table.

           The header section begins the file.  This section  contains  six  short
           integers in the format described below.  These integers are

                (1) the magic number (octal 0432);

                (2) the size, in bytes, of the names section;

                (3) the number of bytes in the boolean section;

                (4) the number of short integers in the numbers section;

                (5) the number of offsets (short integers) in the strings section;

                (6) the size, in bytes, of the string table.

           Short  integers are stored in two 8-bit bytes.  The first byte contains
           the least significant 8 bits of the value, and the second byte contains
           the  most significant 8 bits.  (Thus, the value represented is 256*sec-
           ond+first.)  The value -1 is represented by the two bytes  0377,  0377;
           other  negative values are illegal. This value generally means that the
           corresponding capability is missing from this terminal.  Note that this
           format corresponds to the hardware of the VAX and PDP-11 (that is, lit-
           tle-endian machines).  Machines where this does not correspond  to  the
           hardware  must  read  the integers as two bytes and compute the little-
           endian value.

           The terminal names section comes next.  It contains the first  line  of
           the  terminfo  description, listing the various names for the terminal,
           separated by the "|" character.  The  section  is  terminated  with  an
           ASCII NUL character.

           The  boolean  flags have one byte for each flag.  This byte is either 0
           or 1 as the flag is present or absent.  The  capabilities  are  in  the
           same order as the file <term.h>.

           Between the boolean section and the number section, a null byte will be
           inserted, if necessary, to ensure that the number section begins on  an
           even byte (this is a relic of the PDP-11's word-addressed architecture,
           originally designed in to avoid IOT traps induced by addressing a  word
           on  an  odd  byte boundary).  All short integers are aligned on a short
           word boundary.

           The numbers section is similar to the flags section.   Each  capability
           takes up two bytes, and is stored as a little-endian short integer.  If
           the value represented is -1, the capability is taken to be missing.

           The strings section is also similar.  Each capability is  stored  as  a
           short integer, in the format above.  A value of -1 means the capability
           is missing.  Otherwise, the value is taken as an offset from the begin-
           ning  of the string table.  Special characters in ^X or \c notation are
           stored in their interpreted  form,  not  the  printing  representation.
           Padding  information  $<nn>  and  parameter  information  %x are stored
           intact in uninterpreted form.

           The final section is the string table.  It contains all the  values  of
           string  capabilities  referenced in the string section.  Each string is
           null terminated.

### EXTENDED STORAGE FORMAT

           The previous section describes the conventional terminfo binary format.
           With  some  minor variations of the offsets (see PORTABILITY), the same
           binary format is used in all modern UNIX systems.  Each system  uses  a
           predefined set of boolean, number or string capabilities.

           The ncurses libraries and applications support extended terminfo binary
           format, allowing users to define capabilities which are loaded at  run-
           time.  This extension is made possible by using the fact that the other
           implementations stop reading the terminfo data when they  have  reached
           the  end of the size given in the header.  ncurses checks the size, and
           if it exceeds that due to  the  predefined  data,  continues  to  parse
           according to its own scheme.

           First, it reads the extended header (5 short integers):

                (1)  count of extended boolean capabilities

                (2)  count of extended numeric capabilities

                (3)  count of extended string capabilities

                (4)  size of the extended string table in bytes.

                (5)  last offset of the extended string table in bytes.

           Using the counts and sizes, ncurses allocates arrays and reads data for
           the extended capabilities in the same order as the header information.

           The extended string table  contains  values  for  string  capabilities.
           After  the  end  of these values, it contains the names for each of the
           extended capabilities  in  order,  e.g.,  booleans,  then  numbers  and
           finally strings.

           Applications  which  manipulate  terminal  data can use the definitions
           described in term_variables(3x) which  associate  the  long  capability
           names with members of a TERMTYPE structure.

### EXTENDED NUMBER FORMAT

           On occasion, 16-bit signed integers are not large enough.  With ncurses
           6.1, a new format is introduced by making a few changes to  the  legacy
           format:

           o   a different magic number (0542)

           o   changing  the type for the number array from signed 16-bit integers
               to signed 32-bit integers.

           To maintain compatibility, the library presents the  same  data  struc-
           tures to direct users of the TERMTYPE structure as in previous formats.
           However, that cannot provide callers with the  extended  numbers.   The
           library  uses  a similar but hidden data structure TERMTYPE2 to provide
           data for the terminfo functions.

## PORTABILITY

           Note that it is possible for setupterm to expect  a  different  set  of
           capabilities  than  are actually present in the file.  Either the data-
           base may have been updated since setupterm has been recompiled (result-
           ing  in extra unrecognized entries in the file) or the program may have
           been recompiled more recently than the database was updated  (resulting
           in  missing  entries).  The routine setupterm must be prepared for both
           possibilities - this is why the numbers and sizes are included.   Also,
           new  capabilities must always be added at the end of the lists of bool-
           ean, number, and string capabilities.

           Despite the consistent use of little-endian for numbers and the  other-
           wise  self-describing format, it is not wise to count on portability of
           binary terminfo entries between commercial UNIX versions.  The  problem
           is  that  there  are  at least three versions of terminfo (under HP-UX,
           AIX, and OSF/1) which diverged from System V terminfo after  SVr1,  and
           have  added  extension  capabilities  to  the string table that (in the
           binary format) collide with System V and XSI  Curses  extensions.   See
           terminfo(5)  for  detailed  discussion of terminfo source compatibility
           issues.

           Direct access to the TERMTYPE structure is provided for legacy applica-
           tions.   Portable  applications  should  use  the tigetflag and related
           functions described in curs_terminfo(3x) for reading terminal capabili-
           ties.

## EXAMPLE

           As an example, here is a description for the Lear-Siegler ADM-3, a pop-
           ular though rather stupid early terminal:

             adm3a|lsi adm3a,
                     am,
                     cols#80, lines#24,
                     bel=^G, clear= 32$<1>, cr=^M, cub1=^H, cud1=^J,
                     cuf1=^L, cup=\E=%p1%{32}%+%c%p2%{32}%+%c, cuu1=^K,
                     home=^^, ind=^J,

           and a hexadecimal dump of the compiled terminal description:

             0000  1a 01 10 00 02 00 03 00  82 00 31 00 61 64 6d 33  ........ ..1.adm3
             0010  61 7c 6c 73 69 20 61 64  6d 33 61 00 00 01 50 00  a|lsi ad m3a...P.
             0020  ff ff 18 00 ff ff 00 00  02 00 ff ff ff ff 04 00  ........ ........
             0030  ff ff ff ff ff ff ff ff  0a 00 25 00 27 00 ff ff  ........ ..%.'...
             0040  29 00 ff ff ff ff 2b 00  ff ff 2d 00 ff ff ff ff  ).....+. ..-.....
             0050  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             0060  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             0070  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             0080  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             0090  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             00a0  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             00b0  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             00c0  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             00d0  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             00e0  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             00f0  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             0100  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             0110  ff ff ff ff ff ff ff ff  ff ff ff ff ff ff ff ff  ........ ........
             0120  ff ff ff ff ff ff 2f 00  07 00 0d 00 1a 24 3c 31  ....../. .....$<1
             0130  3e 00 1b 3d 25 70 31 25  7b 33 32 7d 25 2b 25 63  >..=%p1% {32}%+%c
             0140  25 70 32 25 7b 33 32 7d  25 2b 25 63 00 0a 00 1e  %p2%{32} %+%c....
             0150  00 08 00 0c 00 0b 00 0a  00                       ........ .

## LIMITS

           Some limitations:

           o   total compiled entries cannot exceed 4096 bytes in the legacy  for-
               mat.

           o   total  compiled  entries  cannot exceed 32768 bytes in the extended
               format.

           o   the name field cannot exceed 128 bytes.

## FILES

           /usr/local/ncurses/lib/terminfo/*/*     compiled  terminal   capability
           data base

## SEE ALSO

           curses(3x), terminfo(5).

## AUTHORS

           Thomas E. Dickey
           extended terminfo format for ncurses 5.0
           hashed database support for ncurses 5.6
           extended number support for ncurses 6.1

           Eric S. Raymond
           documented legacy terminfo format, e.g., from pdcurses.

                                                                           term(5)