<s>
EDT	B-Application
is	O
a	O
text	B-Application
editor	I-Application
running	O
on	O
the	O
Unisys	O
VS/9	O
operating	B-General_Concept
system	I-General_Concept
using	O
the	O
UNIVAC	B-Device
Series	I-Device
90	I-Device
mainframe	B-Architecture
computers	I-Architecture
,	O
and	O
as	O
of	O
2013	O
runs	O
on	O
the	O
Fujitsu	O
BS2000	B-Application
mainframe	B-Architecture
computer	I-Architecture
and	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
It	O
was	O
developed	O
by	O
RCA	O
for	O
the	O
TSOS	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
for	O
Spectra	B-Device
series	I-Device
mainframes	B-Architecture
.	O
</s>
<s>
The	O
RCA	O
version	O
was	O
later	O
sold	O
to	O
Sperry	O
Univac	O
(	O
which	O
later	O
became	O
Unisys	O
)	O
,	O
and	O
was	O
released	O
for	O
the	O
VS/9	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
Univac/Fujitsu	O
EDT	B-Application
editor	O
is	O
a	O
line-based	O
editor	O
,	O
in	O
that	O
it	O
does	O
not	O
use	O
function	O
keys	O
.	O
</s>
<s>
Unlike	O
editors	O
such	O
as	O
Teco	B-Application
or	O
Emacs	B-Application
,	O
the	O
program	O
is	O
always	O
in	O
text-entry	O
mode	O
,	O
similar	O
to	O
today	O
's	O
word	O
processors	O
.	O
</s>
<s>
One	O
use	O
for	O
this	O
feature	O
is	O
to	O
write	O
scripts	O
to	O
have	O
EDT	B-Application
perform	O
various	O
actions	O
upon	O
another	O
file	O
.	O
</s>
<s>
Because	O
of	O
the	O
ISAM	B-Application
file	O
format	O
which	O
supports	O
an	O
8-character	O
index	O
key	O
,	O
line	O
numbers	O
consist	O
of	O
a	O
floating-point	B-Algorithm
number	I-Algorithm
in	O
the	O
range	O
of	O
0.0000	O
to	O
9999.9999	O
.	O
</s>
<s>
The	O
usual	O
line	O
number	O
supplied	O
by	O
EDT	B-Application
starts	O
at	O
1.000	O
and	O
is	O
incremented	O
by	O
1	O
as	O
each	O
new	O
line	O
was	O
added	O
.	O
</s>
<s>
Commands	O
in	O
EDT	B-Application
generally	O
consist	O
of	O
a	O
command	O
(	O
which	O
is	O
case	O
insensitive	O
)	O
,	O
which	O
may	O
be	O
followed	O
by	O
a	O
range	O
of	O
line	O
numbers	O
that	O
the	O
command	O
was	O
to	O
act	O
upon	O
,	O
and	O
a	O
subfunction	O
indicating	O
how	O
the	O
command	O
is	O
to	O
act	O
.	O
</s>
<s>
possibly	O
one	O
of	O
the	O
first	O
programs	O
(	O
the	O
Univac	B-Device
90/60	I-Device
goes	O
back	O
to	O
the	O
late	O
1960s	O
and	O
early	O
1970s	O
)	O
to	O
support	O
the	O
use	O
of	O
plugins	B-Application
to	O
allow	O
other	O
programs	O
to	O
use	O
the	O
text	O
the	O
editor	O
held	O
in	O
memory	O
,	O
as	O
well	O
as	O
send	O
commands	O
back	O
to	O
the	O
editor	O
for	O
processing	O
.	O
</s>
<s>
Fujitsu	O
's	O
current	O
release	O
of	O
EDT	B-Application
also	O
supports	O
Unicode	O
,	O
which	O
did	O
not	O
exist	O
when	O
Univac	O
released	O
its	O
version	O
of	O
EDT	B-Application
.	O
</s>
