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From: gwyn@brl-smoke.ARPA (Doug Gwyn )
Newsgroups: comp.sys.att,comp.editors
Subject: Re: vi editor problem on UNIX-pc
Message-ID: <6743@brl-smoke.ARPA>
Date: Wed, 25-Nov-87 22:09:11 EST
Article-I.D.: brl-smok.6743
Posted: Wed Nov 25 22:09:11 1987
Date-Received: Sun, 29-Nov-87 12:21:18 EST
References: <50@cjsa.UUCP> <113@ghostwheel.UUCP> <1475@ttidca.TTI.COM> <7793@reed.UUCP>
Reply-To: gwyn@brl.arpa (Doug Gwyn (VLD/VMB) )
Organization: Ballistic Research Lab (BRL), APG, MD.
Lines: 48
Xref: mnetor comp.sys.att:1884 comp.editors:32

In article <7793@reed.UUCP> bart@reed.UUCP (Bart Massey) writes:
>The "xn" termcap entry indicates the magic DEC wrapmargin feature ...

No!  The VT100 right-margin behavior is NOT correctly described by "xn";
there is NO correct way to completely characterize the VT100's right-margin
behavior, which is much weirder than most people realize, solely by means of
combinations of termcap capabilities.

Here is the VT100 termcap entry we use at BRL; note that it specifies
neither "am" nor "xn":

#
# DEC VT100
# The "vt100" entry supports the Advanced Video Option if present;
# however, AVO is not required for correct operation of the "vt100" entry.
# The following SET-UP modes are assumed for normal operation:
#	ANSI_MODE	AUTO_XON/XOFF_ON	NEWLINE_OFF	80_COLUMNS
# Other SET-UP modes may be set for operator convenience or communication
# requirements; I recommend
#	SMOOTH_SCROLL	AUTOREPEAT_ON	BLOCK_CURSOR	MARGIN_BELL_OFF
#	SHIFTED_3_#	WRAP_AROUND_ON
# Unless you have a graphics add-on such as Digital Engineering's VT640
# (and even then, whenever it can be arranged!) you should set
#	INTERLACE_OFF
# Hardware tabs are assumed to be set every 8 columns; they can be set up
# by the "reset" or "tabs" utility (use vt100-x, 132 columns, for this).
# I have included some compatible code in "rs" for the VT640 if you have one.
# No delays are specified; use "stty ixon -ixany" to enable DC3/DC1 flow control!
d0|vt100|DEC VT100:\
	:ae=^O:as=^N:bl=^G:cd=\E[J:ce=\E[K:cm=\E[%i%d;%dH:co#80:cr=^M:\
	:cs=\E[%i%d;%dr:ct=\E[3g:DO=\E[%dB:do=^J:ho=\E[H:is=\E<\E)0:it#8:\
	:k0=\EOP:k1=\EOQ:k2=\EOR:k3=\EOS:kb=^H:kd=\EOB:ke=\E[?1l\E>:kl=\EOD:\
	:kr=\EOC:ks=\E[?1h\E=:ku=\EOA:l0=PF1:l1=PF2:l2=PF3:l3=PF4:LE=\E[%dD:\
	:le=^H:li#24:ll=\E[24H:mb=\E[5m:md=\E[1m:me=\E[m:mr=\E[7m:ms:nd=\E[C:\
	:nw=\EE:rc=\E8:RI=\E[%dC:\
	:rs=^X\E<\E2\E[?9h^]\E^L^X\E[20l\E[?3;9;6l\E[r\E[m\E[q\E(B^O\E)0\E>:\
	:sc=\E7:se=\E[m:sf=^J:so=\E[7m:sr=\EM:st=\EH:ta=^I:ue=\E[m:UP=\E[%dA:\
	:up=\EM:us=\E[4m:vt#3:xo:\
	:cl=\E[H\E[J:\
	:bs:kn#4:pt:
d8|vt100-w|DEC VT100 with AVO in 132-column mode:\
	:co#132:\
	:rs=^X\E<\E2\E[?9h^]\E^L^X\E[20l\E[?9;6l\E[?3h\
\E[r\E[m\E[q\E(B^O\E)0\E>:\
	:tc=vt100:
d9|vt100-x|DEC VT100 without AVO in 132-column mode:\
	:li#14:ll=\E[14H:\
	:tc=vt100-w: