<s>
TRON	B-Language
is	O
a	O
debugging	O
command	O
in	O
old	O
dialects	O
of	O
the	O
BASIC	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
It	O
was	O
used	O
primarily	O
for	O
debugging	O
line-numbered	B-Application
BASIC	O
GOTO	B-Application
and	O
GOSUB	B-Device
statements	O
.	O
</s>
<s>
In	O
text-mode	O
environments	O
such	O
as	O
the	O
TRS-80	B-Device
or	O
DOS	B-Device
,	O
it	O
would	O
print	O
the	O
current	O
line	B-Application
number	I-Application
which	O
was	O
being	O
executed	O
,	O
on-screen	O
.	O
</s>
<s>
In	O
a	O
windowed	O
environment	O
,	O
when	O
the	O
TRON	B-Language
command	I-Language
had	O
been	O
executed	O
,	O
a	O
window	O
would	O
indicate	O
the	O
line	B-Application
number	I-Application
being	O
executed	O
at	O
that	O
instant	O
.	O
</s>
<s>
This	O
command	O
's	O
opposite	O
is	O
TROFF	B-Language
,	O
or	O
TRace	O
OFF	O
,	O
used	O
to	O
turn	O
off	O
command	O
tracing	O
.	O
</s>
<s>
TRON	B-Language
and	O
TROFF	B-Language
were	O
made	O
obsolete	O
by	O
the	O
advent	O
of	O
multitasking	O
windowing	O
environments	O
,	O
which	O
permit	O
a	O
developer	O
to	O
switch	O
back	O
and	O
forth	O
between	O
program	O
output	O
and	O
source	O
code	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
TRON/TROFF	O
are	O
no	O
longer	O
supported	O
by	O
most	O
current	O
BASIC	O
dialects	O
,	O
including	O
Microsoft	O
Visual	B-Language
Basic	I-Language
.	O
</s>
