_features.txt

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.*s 1 "Features"
.*s 2 "Supported Terminals"

ECU supports many terminals with geometries between 20 and 43
lines, inclusive.  The column width must be 80.
The termcap entry for a console (user tty rather than the line)
MUST contain a valid entry for the database entries listed below.

ECU does not attempt to support terminal emulation in the classic
sense of the word.  It presents to the remote host an "ANSI-like"
terminal type as described earlier in the introduction and in 
the section titled "ANSI Filter."
However, it does support, with limitations, any LOCAL terminal
(console) for which a valid termcap description exists. You MAY
be able to use ECU with a remote terminal (calling into UNIX/XENIX
over a network or modem), but you may get unfavorable results with
function key usage if your modem is a "packetizing" type, such as
a Telebit or if ethernet or other networking chops up your keystroke
sequences.  ECU allows approximately 100 milliseconds after receiving
an ASCII ESC character for later characters of a function key sequence
to arrive.  If at least one character of the sequence has not been
received in that time, ECU treats the key as an ESCape, not a function key.
This typical problem of detecting ESC vs. function key is unfortunate, but
we must live with it until paradigms change (say, in about 2010?).

The termcap entry for a console
MUST contain a valid entry for the following database entries:

.DS L
cl      clear screen
kl      cursor left
kr      cursor right
dc      delete character
dl      delete line
cd      clear to end of display
ce      clear to end of line
ic      insert character
al      insert line ("add" a "line")
cm      cursor motion
so      stand out (terminal specific attention getter)
se      stand end
.DE

The above sequences MUST be present, valid and reasonably
efficient.  ECU does not use curses during it's primary mode of
operation (keyboard send-receive). Unlike curses, ECU makes no
attempt to emulate missing terminal functionality.  Failure to
provide valid entries will result in strange behavior with no
warning.

Note that the formal termcap description of "kl" and "kr" 
state these are sequences generated by the terminal
.B keyboard ,
but ECU expects that these sequences also cause the desired
effects when
.B sent
to the
.B screen .

Additionally, the following, optional, sequences will be used if
they are detected.

.DS L
mb      bold on ("XENIX" extension)
me      bold off ("XENIX" extension)
us      underscrore on
ue      underscrore off
vb      visual bell
.DE

On SCO, termcap terminal contrtol is used.  Other
versions use terminfo.
A future SCO version of ECU may use terminfo instead of termcap.
Problems with terminfo prevent its use at the present time.
In addition, early versions of XENIX do not support terminfo.

On SCO multiscreens, SCO "extensions" to "ANSI" are supported
as described below in "Multiscreen Local Terminals."

.*s 2 "Host Video Control Sequences"

.*s 3 "All Local Consoles (Terminals)"

The following sequences are recieved over the line
by ECU and properly interpreted for all local terminal types
(multiscreen, rlogin/xterm pseudotty, serial).

.DS L
Sequence  | Description
----------+-------------------------------
ESC [ @   | ICH
ESC [ A   | CUU
ESC [ B   | CUD
ESC [ C   | CUF
ESC [ D   | CUB
ESC [ E   | CNL       See ANSI X3.64,
ESC [ F   | CPL       screen(HW) and/or
ESC [ H   | CUP       MS-DOS Technical
ESC [ J   | ED        Reference Manual
ESC [ K   | EL
ESC [ L   | IL
ESC [ M   | DL
ESC [ P   | DCH
ESC [ S   | SU
ESC [ T   | SD
ESC [ X   | ECH
ESC [ `   | HPA
ESC [ a   | HPR
ESC [ d   | VPA
ESC [ e   | VPR
ESC [ f   | HVP
ESC [ ? m | SGR
ESC [ n   | DSR
ESC [ s   | save cursor MS-DOSism
ESC [ u   | restore cursor MS-DOSism
.DE
.DS L
SGR Sequences for ALL TERMINALS
Sequence  | Description   |  Maps to termcap
----------+---------------+-------------------------------
ESC [ 0 m | normal        |  "se"+"me"+"ue"
ESC [ 1 m | bold          |  "so"
ESC [ 4 m | underscore    |  "us"
ESC [ 5 m | blink         |  "mb" (XENIX extension)
ESC [ 7 m | reverse video |  "so"
.DE

.*s 3 "Multiscreen Local Terminals"

In addition to the above, if you are operating from an SCO color
multiscreen, additional (SCO and MS-DOS/ANSI.SYS) sequences
are supported (see screen(HW)):

.DS L
Additional Multiscreen SGR Sequences
Sequence    | Description  (no termcap mapping)
------------+-----------------------------------------------
ESC [ 8 m   | non-display
ESC [ 1 0 m | select primary font
ESC [ 1 1 m | select first alternate font (0x00-0x1F)
ESC [ 1 2 m | select second alternate font (0x80-0xFF)
ESC [ 3 0 m | black foreground
ESC [ 3 1 m | red foreground
ESC [ 3 2 m | green foreground
ESC [ 3 3 m | brown foreground
ESC [ 3 4 m | blue foreground
ESC [ 3 5 m | magenta foreground
ESC [ 3 6 m | cyan foreground
ESC [ 3 7 m | white foreground
ESC [ 3 8 m | enables underline option
ESC [ 3 9 m | disables underline option
ESC [ 4 0 m | black background
ESC [ 4 1 m | red background
ESC [ 4 2 m | green background
ESC [ 4 3 m | brown background
ESC [ 4 4 m | blue background
ESC [ 4 5 m | magenta background
ESC [ 4 6 m | cyan background
ESC [ 4 7 m | white background
.DE

.s 3 "MS-DOS 'SGR Gaggles'"

ECU also does it's best to interpret MS-DOS "SGR gaggles" such as
.DS I
ESC [ 5 ; 3 4 ; 4 7 m
.DE
which means "set the terminal to white background with
blue blinking foreground."

.*s 3 "Character Mapping"

Most versions of ECU running on an AT style machine attempt to
use the ruling characters in the video display adapter's ROM
per:
.DS L
Mapped Characters (see pc_scr.h):
Hex  | Description
-----+---------------------------
0xDA | top left single rule
0xBF | top right single rule
0xC0 | bottom left single rule
0xD9 | bottom right single rule
0xC3 | left hand T
0xB4 | right hand T
0xB3 | vertical rule
0xC4 | horizontal rule
.DE
On non-AT machines (or in such environments as X11), the PC ROM
single ruling characters from the following table are mapped
after the fashion of:
.DS L
       .-----+--------.
       |     |        |
       |     +--------+
       |     |        |
       +-----+        |
       |     |        |
       `-----+--------'
.DE

(Due to laziness on the part of the author, double
ruling characters will appear as random druk, unless your terminal
has joined the Church of the True-Blue ROM.
One day an X version of this program may appear and you can choose
to no longer accomplish real work, but may spend your days editing
42Kb resource files which will give you TAC, Total Anal Control,
over all this.)

.*s 2 "Function Key Mapping (Recognition)"

(This section reflects the changes in keyboard management made
in version 3.20.)

ECU recognizes 23 function keys as having special significance
to its operation.
They are:
.DS I
Name      Description 
--------  ------------
F1        F1         
F2        F2        
F3        F3          
F4        F4          
F5        F5          
F6        F6          
F7        F7          
F8        F8          
F9        F9          
F10       F10         
F11       F11         
F12       F12         
Home      Home        
End       End         
PgUp      Page up     
PgDn      Page down   
CUU       Up arrow    
CUD       Down arrow  
CUL       Left arrow  
CUR       Right arrow 
CU5       "Cursor 5"  
Ins       Insert      
BkTab     Back Tab    
.DE

ECU matches a function key sequence
to an internal function key representation
by testing all keystroke sequences against an internal table loaded
at the beginning of execution from the file ~/.ecu/funckeymap.
A default funckeymap file placed in the ECU library directory
(normally /usr/local/lib/ecu) by the software installation process.  
If there is no funckeys in the user's home directory, the default
file is used.

NOTE that supported terminals MUST employ function keys which generate
sequences less than 32 characters in length.

X11 xterms and X terminals usually require special attention
with VT100.Translations overrides.  Sometimes an xmodmap must also be
employed.  Experimentation is the best teacher, but the supplied
funckeymap file and various READMEs offer some hints.  In particular,
README.KEYBRD contains information that is kept current.

Several predefined entries are supplied with the program distribution
in models/funckeymap.
If you have a terminal or console with a keyboard not already
in this file, you must construct one using the terminal's reference
manual or by direct discovery (typing the key and empricially noting
its generated sequence).
The program kbdtest3 (the source is provided in the distribution) can
assist you in building funckeymap entries.
certain keys are pressed.  kbdtest.c is a more primitive version of
the same program.

Normally, the TERM environment variable is used to determine
the funckeymap entry to be used.  Sometimes, the TERM variable
is not adequate for identifying your keyboard arrangement.  For
instance, suppose you use an xterm on the console at times and
an X terminal at other times.  The choice of function keys
and the character sequences they emit are not likely to match.
Rather than make herculean efforts with xmodmap and translations,
you can define two different funckeymap entries, say "xterm-sco"
and "xterm-ncd".
The environment variable ECUFUNCKEY, if found, overrides the
TERM variable for funckeymap keyboard management only.  
TERM is always used for identifying the display.
Thus, you can set TERM to "xterm" and ECUFUNCKEY to "xterm-sco"
OR "xterm-ncd".
Also, the -F command line switch may be used (which overrides $ECUFUNCKEY).

The format of an file entry is shown below.
Lines beginning with '#' are comments.

.DS I
#+------------------------------
# SCO
#-------------------------------
ansi
ansi43
sco
    F1:F1:          esc [ M 
    F2:F2:          esc [ N 
    F3:F3:          esc [ O 
    F4:F4:          esc [ P 
    F5:F5:          esc [ Q 
    F6:F6:          esc [ R 
    F7:F7:          esc [ S 
    F8:F8:          esc [ T 
    F9:F9:          esc [ U 
    F10:F10:        esc [ V 
    F11:F11:        esc [ W 
    F12:F12:        esc [ X 
    Home:Home:      esc [ H 
    End:End:        esc [ F 
    PgUp:PgUp:      esc [ I 
    PgDn:PgDn:      esc [ G 
    CUU:CUU:        esc [ A 
    CUL:CUL:        esc [ D 
    CU5:CU5:        esc [ E 
    CUR:CUR:        esc [ C 
    CUD:CUD:        esc [ B 
    Ins:Ins:        esc [ L
    BkTab:BackTab:  esc [ Z
.DE

The first line(s) in a terminal keyboard description begin in
column 1 and contain the terminal types (a la $TERM) for which
the keyboard description are valid.  The example entry contains
several references to terminal types containing the substring
'ansi'.  These are included only as an example of one keyboard
description servicing multiple terminal types.

Following the "first lines" are key definition entries, each
preceded by at least one tab or space.  Each entry is composed of
three fields delimited by commas.  The first field of an entry is
the internal ECU function key name and must be chosen from the
following strings (with no regard to case): "F1", "F2", "F3",
"F4", "F5", "F6", "F7", "F8", "F9", "F10", "F11", "F12", "Home",
"End", "PgUp", "PgDn", "CUU" (cursor up), "CUL" (cursor left),
"CU5" (unshifted cursor pad 5), "CUR" (cursor right) and "CUD"
(cursor down). The
second field contains the name of the key as it appears on the
keyboard (such as "F16" for End on the Wyse 60).  The
third field is a description of the character sequence generated
by the keyboard when the chosen key is pressed; it is a
string of one or more tokens separated by spaces or tabs.

In addition, function key sequences may not 
exceed 31 characters in length.

PLEASE NOTE: ECU does not have a reasonable way for you to terminate it
if there are no Home and End keys defined, so it refuses to proceed
if no definitions are found.  Even so, if you have incorrect definitions,
you may not be able to get out of ECU without a kill -1 <pid> from
another terminal or hanging up your connection with UNIX/XENIX