<s>
The	O
programming	O
language	O
APL	B-Language
uses	O
a	B-Language
number	I-Language
of	I-Language
symbols	I-Language
,	O
rather	O
than	O
words	O
from	O
natural	O
language	O
,	O
to	O
identify	O
operations	O
,	O
similarly	O
to	O
mathematical	O
symbols	O
.	O
</s>
<s>
Prior	O
to	O
the	O
wide	O
adoption	O
of	O
Unicode	O
,	O
a	O
number	O
of	O
special-purpose	O
EBCDIC	B-Language
and	O
non-EBCDIC	O
code	O
pages	O
were	O
used	O
to	O
represent	O
the	O
symbols	O
required	O
for	O
writing	O
APL	B-Language
.	O
</s>
<s>
Due	O
to	O
its	O
origins	O
on	O
IBM	O
Selectric-based	O
teleprinters	O
,	O
APL	B-Language
symbols	I-Language
have	O
traditionally	O
been	O
represented	O
on	O
the	O
wire	O
using	O
a	O
unique	O
,	O
non-standard	O
character	O
set	O
.	O
</s>
<s>
In	O
the	O
1960s	O
and	O
1970s	O
,	O
few	O
terminal	O
devices	O
existed	O
which	O
could	O
reproduce	O
them	O
,	O
the	O
most	O
popular	O
ones	O
being	O
the	O
IBM	O
2741	O
and	O
IBM	B-Device
1050	I-Device
fitted	O
with	O
a	O
specific	O
APL	B-Language
print	O
head	O
.	O
</s>
<s>
Over	O
time	O
,	O
with	O
the	O
universal	O
use	O
of	O
high-quality	O
graphic	O
display	O
,	O
printing	O
devices	O
and	O
Unicode	O
support	O
,	O
the	O
APL	B-Language
character	O
font	O
problem	O
has	O
largely	O
been	O
eliminated	O
.	O
</s>
<s>
IBM	O
assigns	O
the	O
following	O
character	O
IDs	O
(	O
GCGIDs	O
)	O
to	O
APL	B-Language
syntax	I-Language
,	O
which	O
are	O
used	O
in	O
the	O
definitions	O
of	O
its	O
code	O
pages	O
.	O
</s>
<s>
+	O
"	O
SL	O
"	O
(	O
APL	B-Language
functional	O
symbol	O
)	O
series	O
GCGIDsGCGID	O
IBM	O
name	O
Unicode	O
Notes	O
and	O
other	O
mappingsSL010000	O
Up	O
Stile	O
(	O
APL	B-Language
)	O
SL020000	O
Down	O
Stile	O
(	O
APL	B-Language
)	O
SL030000	O
Del	O
(	O
APL	B-Language
)	O
SL040000	O
Del	O
Tilde	O
(	O
APL	B-Language
)	O
SL050000	O
Del	O
Stile	O
(	O
APL	B-Language
)	O
SL060000	O
Delta	O
(	O
APL	B-Language
)	O
SL070000	O
Delta	O
Stile	O
(	O
APL	B-Language
)	O
SL080000	O
Circle	O
(	O
APL	B-Language
)	O
This	O
is	O
SM750000	O
in	O
a	O
non-APL	O
context	O
,	O
for	O
example	O
,	O
in	O
the	O
C0	O
replacement	O
graphics	O
from	O
code	O
page	O
437	O
,	O
which	O
code	O
pages	O
907	O
,	O
909	O
and	O
910	O
inherit	O
some	O
or	O
all	O
of	O
,	O
retaining	O
SM750000	O
in	O
the	O
C0	O
area	O
and	O
also	O
including	O
SL080000	O
outside	O
of	O
it	O
.	O
</s>
<s>
Both	O
map	O
to	O
U+25CB	O
when	O
APL	B-Language
is	O
represented	O
using	O
Unicode	O
characters	O
,	O
although	O
SL080000	O
can	O
be	O
mapped	O
to	O
U+F890	O
in	O
IBM	O
's	O
private	O
use	O
area	O
scheme	O
.	O
</s>
<s>
(	O
Included	O
with	O
)	O
Compare	O
SL590000	O
through	O
SL620000	O
below.SL090000	O
Circle	O
Stile	O
(	O
APL	B-Language
)	O
SL100000	O
Circle	O
Slope	O
(	O
APL	B-Language
)	O
SL110000	O
Circle	O
Star	O
(	O
APL	B-Language
)	O
SL120000	O
Circle	O
Bar	O
SL130000	O
Quad	O
Quote	O
(	O
APL	B-Language
)	O
SL140000	O
Quad	O
Divide	O
(	O
APL	B-Language
)	O
SL150000	O
Slash	O
Bar	O
(	O
APL	B-Language
)	O
SL160000	O
Slope	O
Bar	O
(	O
APL	B-Language
)	O
SL170000	O
Up	O
Caret	O
Tilde	O
(	O
APL	B-Language
)	O
SL180000	O
Down	O
Caret	O
Tilde	O
(	O
APL	B-Language
)	O
SL190000	O
Down	O
Tack	O
Jot	O
(	O
APL	B-Language
)	O
SL200000	O
Up	O
Tack	O
Jot	O
(	O
APL	B-Language
)	O
SL210000	O
Up	O
Shoe	O
Null	O
(	O
APL	B-Language
)	O
SL220000	O
Up	O
Tack	O
(	O
APL	B-Language
)	O
SL230000	O
Down	O
Tack	O
(	O
APL	B-Language
)	O
SL240000	O
Down	O
Tack	O
Up	O
Tack	O
(	O
APL	B-Language
)	O
SL250000	O
Jot	O
(	O
APL	B-Language
)	O
SL260000	O
SL270000	O
Quad	O
Jot	O
(	O
APL	B-Language
)	O
SL280000	O
Quad	O
Slope	O
(	O
APL	B-Language
)	O
SL290000	O
Ampersand	O
Underbar	O
Not	O
used	O
in	O
any	O
documented	O
code	O
page	O
.	O
</s>
<s>
Can	O
be	O
represented	O
in	O
Unicode	O
with	O
the	O
sequence	O
&̲SL300000	O
Equal	O
Underbar	O
(	O
APL	B-Language
)	O
SL310000	O
OUT	O
Symbol	O
(	O
APL	B-Language
)	O
Not	O
used	O
in	O
any	O
documented	O
code	O
page	O
.	O
</s>
<s>
Reference	O
glyph	O
resembles	O
oblique	O
underlined	O
forms	O
of	O
the	O
letters	O
O	O
,	O
U	O
and	O
T	O
overstruck	O
in	O
the	O
same	O
character	O
position.SL320000	O
Diaeresis	O
Dot	O
(	O
APL	B-Language
)	O
SL330000	O
Delta	O
Underbar	O
(	O
APL	B-Language
)	O
SL340000	O
Left	O
Tack	O
(	O
APL	B-Language
)	O
SL350000	O
Right	O
Tack	O
(	O
APL	B-Language
)	O
SL360000	O
Quad	O
(	O
APL	B-Language
)	O
SL370000	O
Less	O
Greater	O
(	O
APL	B-Language
)	O
,	O
SL380000	O
Stile	O
(	O
APL	B-Language
)	O
,	O
SL400000	O
Up	O
Shoe	O
(	O
APL	B-Language
)	O
SL410000	O
Down	O
Shoe	O
(	O
APL	B-Language
)	O
SL420000	O
Left	O
Shoe	O
(	O
APL	B-Language
)	O
SL430000	O
Right	O
Shoe	O
(	O
APL	B-Language
)	O
SL440000	O
Underbar	O
(	O
APL	B-Language
)	O
SL450000	O
Diaeresis	O
(	O
APL	B-Language
)	O
SL460000	O
Tilde	O
(	O
APL	B-Language
)	O
U+F88F	O
in	O
IBM	O
's	O
private	O
use	O
area	O
scheme	O
.	O
</s>
<s>
Also	O
mapped	O
to	O
,	O
although	O
SD190000	O
(	O
U+007E	O
in	O
a	O
non-APL	O
context	O
)	O
co-occurs	O
at	O
0xA1	O
(	O
while	O
SL460000	O
is	O
at	O
0x80	O
)	O
in	O
code	O
page	O
213.SL480000	O
Circle	O
Plus	O
SL490000	O
Circle	O
x	O
SL500000	O
Down	O
Caret	O
(	O
APL	B-Language
)	O
SL510000	O
Up	O
Caret	O
(	O
APL	B-Language
)	O
SL520000	O
Less	O
(	O
APL	B-Language
)	O
SL530000	O
Greater	O
(	O
APL	B-Language
)	O
SL540000	O
Divide	O
(	O
APL	B-Language
)	O
SL550000	O
Times	O
(	O
APL	B-Language
)	O
SL560000	O
Not	O
Greater	O
(	O
APL	B-Language
)	O
SL570000	O
Not	O
Less	O
(	O
APL	B-Language
)	O
SL580000	O
Quote	O
Dot	O
(	O
APL	B-Language
)	O
U+F88E	O
in	O
IBM	O
's	O
private	O
use	O
area	O
scheme	O
.	O
</s>
<s>
SP020000	O
(	O
in	O
a	O
non-APL	O
context	O
)	O
co-occurs	O
at	O
0x5A	O
in	O
code	B-Language
page	I-Language
293	I-Language
(	O
SL580000	O
is	O
at	O
0xDB	O
in	O
code	O
pages	O
293	O
and	O
310	O
)	O
.	O
</s>
<s>
Tachyonsoft	O
lists	O
for	O
SL580000.SL590000	O
Left	O
Arrow	O
(	O
APL	B-Language
)	O
These	O
arrows	O
are	O
SM300000	O
,	O
SM310000	O
,	O
SM320000	O
and	O
SM330000	O
respectively	O
in	O
a	O
non-APL	O
context	O
,	O
for	O
example	O
,	O
in	O
the	O
C0	O
replacement	O
graphics	O
from	O
code	O
page	O
437	O
,	O
which	O
code	O
pages	O
907	O
,	O
909	O
and	O
910	O
inherit	O
some	O
or	O
all	O
of	O
.	O
</s>
<s>
Their	O
APL	B-Language
GCGIDs	O
can	O
be	O
mapped	O
to	O
U+F88D	O
,	O
U+F88C	O
,	O
U+F88B	O
and	O
U+F88A	O
respectively	O
in	O
IBM	O
's	O
private	O
use	O
area	O
scheme	O
.	O
</s>
<s>
Code	O
pages	O
907	O
and	O
910	O
keep	O
the	O
non-APL	O
GCGIDs	O
for	O
the	O
C0	O
replacements	O
but	O
use	O
the	O
APL	B-Language
GCGIDs	O
where	O
the	O
arrows	O
appear	O
outside	O
of	O
the	O
C0	O
area	O
,	O
while	O
code	O
page	O
909	O
uses	O
the	O
APL	B-Language
GCGIDs	O
multiple	O
times	O
,	O
both	O
for	O
the	O
C0	O
replacements	O
and	O
for	O
between	O
one	O
and	O
two	O
occurrences	O
of	O
each	O
of	O
these	O
arrows	O
outside	O
of	O
the	O
C0	O
area	O
.	O
</s>
<s>
Duplicating	O
C0	O
replacement	O
graphics	O
outside	O
of	O
the	O
C0	O
area	O
is	O
not	O
an	O
uncommon	O
practice	O
in	O
DOS	O
code	O
pages	O
:	O
compare	O
,	O
for	O
example	O
,	O
the	O
pilcrow	O
and	O
section	O
sign	O
in	O
code	O
page	O
850.SL600000	O
Right	O
Arrow	O
(	O
APL	B-Language
)	O
SL610000	O
Up	O
Arrow	O
(	O
APL	B-Language
)	O
SL620000	O
Down	O
Arrow	O
(	O
APL	B-Language
)	O
SL630000	O
Overbar	O
(	O
APL	B-Language
)	O
SL640000	O
Slope	O
(	O
APL	B-Language
)	O
U+F889	O
in	O
IBM	O
's	O
private	O
use	O
area	O
scheme	O
.	O
</s>
<s>
Code	B-Language
page	I-Language
293	I-Language
(	O
CCSID	O
293	O
)	O
,	O
called	O
"	O
APL	B-Language
(	O
USA	O
)	O
"	O
,	O
is	O
an	O
EBCDIC	B-Language
code	O
page	O
which	O
includes	O
APL	B-Language
symbols	I-Language
,	O
in	O
addition	O
to	O
preserving	O
the	O
basic	O
Latin	O
letters	O
and	O
Western	O
Arabic	O
numerals	O
at	O
their	O
usual	O
EBCDIC	B-Language
locations	O
.	O
</s>
<s>
Code	B-Language
page	I-Language
310	I-Language
(	O
"	O
Graphic	O
Escape	O
APL/TN	O
"	O
)	O
includes	O
a	O
larger	O
gamut	O
of	O
symbols	O
,	O
but	O
does	O
not	O
itself	O
include	O
the	O
basic	O
Latin	O
letters	O
or	O
the	O
basic	O
digits	O
.	O
</s>
<s>
It	O
is	O
used	O
alongside	O
Code	O
page	O
37-2	O
,	O
with	O
the	O
Code	B-Language
page	I-Language
310	I-Language
codes	O
being	O
prefixed	O
by	O
the	O
Graphic	O
Escape	O
(	O
EBCDIC	B-Language
0x08	O
)	O
control	O
character	O
.	O
</s>
<s>
Code	B-Language
page	I-Language
351	I-Language
(	O
"	O
GDDM	O
Default	O
(	O
USA	O
)	O
"	O
)	O
contains	O
most	O
of	O
the	O
characters	O
of	O
Code	B-Language
page	I-Language
293	I-Language
and	O
Code	B-Language
page	I-Language
310	I-Language
(	O
except	O
⍷	B-Language
,	O
epsilon	O
with	O
underline	O
)	O
in	O
addition	O
to	O
the	O
letters	O
and	O
digits	O
,	O
by	O
replacing	O
several	O
control	O
characters	O
with	O
symbols	O
.	O
</s>
<s>
Code	B-Language
page	I-Language
371	I-Language
,	O
registered	O
for	O
use	O
with	O
ISO/IEC	O
2022	O
as	O
ISO-IR-68	B-Language
,	O
is	O
a	O
7-bit	O
heavily	O
modified	O
ASCII	O
,	O
designed	O
by	O
the	O
APL	B-Language
Working	O
Group	O
of	O
the	O
Canadian	O
Standards	O
Association	O
,	O
intended	O
for	O
use	O
with	O
APL	B-Language
in	O
an	O
environment	O
allowing	O
overstriking	B-Application
of	O
characters	O
using	O
the	O
(	O
backspace	O
,	O
0x08	O
)	O
control	O
code	O
.	O
</s>
<s>
Code	O
page	O
909	O
is	O
another	O
encoding	O
for	O
APL	B-Language
,	O
differing	O
from	O
code	O
page	O
907	O
in	O
not	O
including	O
the	O
underlined	O
characters	O
,	O
assigning	O
different	O
codes	O
to	O
the	O
APL	B-Language
characters	O
which	O
fall	O
in	O
the	O
0xB0	O
–	O
DF	O
range	O
,	O
and	O
replacing	O
some	O
of	O
the	O
C0	O
replacement	O
graphics	O
from	O
code	O
page	O
437	O
with	O
alternative	O
encodings	O
for	O
certain	O
APL	B-Language
symbols	I-Language
.	O
</s>
<s>
Most	O
APL	B-Language
symbols	I-Language
are	O
present	O
in	O
Unicode	O
,	O
in	O
the	O
Miscellaneous	O
Technical	O
range	O
,	O
although	O
some	O
APL	B-Language
products	O
may	O
not	O
yet	O
feature	O
Unicode	O
,	O
and	O
some	O
APL	B-Language
symbols	I-Language
may	O
be	O
unused	O
or	O
unavailable	O
in	O
a	O
given	O
vendor	O
's	O
implementation	O
.	O
</s>
<s>
As	O
of	O
2010	O
,	O
Unicode	O
allows	O
APL	B-Language
to	O
be	O
stored	O
in	O
text	O
files	O
,	O
published	O
in	O
print	O
and	O
on	O
the	O
web	O
,	O
and	O
shared	O
through	O
email	O
and	O
instant	O
messaging	O
.	O
</s>
<s>
Entering	O
APL	B-Language
characters	O
still	O
requires	O
the	O
use	O
of	O
either	O
a	O
specific	O
input	B-General_Concept
method	I-General_Concept
editor	I-General_Concept
or	O
keyboard	O
mapping	O
,	O
or	O
of	O
a	O
specific	O
touch	O
interface	O
.	O
</s>
<s>
APL	B-Language
keyboard	O
mappings	O
are	O
available	O
for	O
free	O
for	O
the	O
most	O
common	O
operating	O
systems	O
,	O
or	O
can	O
be	O
obtained	O
by	O
adding	O
the	O
Unicode	O
APL	B-Language
symbols	I-Language
to	O
existing	O
keyboard	O
map	O
.	O
</s>
<s>
Missing	O
from	O
Unicode	O
are	O
the	O
traditional	O
underscored	O
alphabetic	O
characters	O
included	O
in	O
some	O
of	O
the	O
APL	B-Language
code	O
pages	O
;	O
their	O
usage	O
has	O
been	O
eliminated	O
or	O
deprecated	O
in	O
most	O
APL	B-Language
implementations	O
.	O
</s>
<s>
These	O
were	O
produced	O
on	O
APL	B-Language
printing	O
terminals	O
by	O
over-striking	O
a	O
straight	O
capital	O
letter	O
with	O
an	O
underscore	O
character	O
.	O
</s>
<s>
IBM	O
assigns	O
them	O
GCGIDs	O
as	O
"	O
LA480000	O
"	O
(	O
which	O
they	O
name	O
"	O
A	O
Line	O
Below	O
Capital/A	O
Underscore	O
(	O
APL	B-Language
)	O
"	O
)	O
,	O
"	O
LB480000	O
"	O
(	O
"	O
B	O
Line	O
Below	O
Capital/B	O
Underscore	O
(	O
APL	B-Language
)	O
"	O
)	O
and	O
so	O
forth	O
,	O
under	O
the	O
"	O
L	O
"	O
series	O
used	O
for	O
Latin	O
letters	O
.	O
</s>
<s>
However	O
,	O
this	O
does	O
not	O
cover	O
the	O
entire	O
ISO	O
basic	O
Latin	O
alphabet	O
,	O
and	O
IBM	O
's	O
reference	O
glyphs	O
for	O
the	O
APL	B-Language
characters	O
show	O
them	O
both	O
underlined	O
and	O
oblique	O
,	O
and	O
tables	O
simulating	O
them	O
with	O
markup	O
may	O
follow	O
suit	O
.	O
</s>
<s>
Note	O
the	O
mnemonics	O
associating	O
an	O
APL	B-Language
character	O
with	O
a	O
letter	O
:	O
(	O
question	O
mark	O
)	O
on	O
,	O
(	O
power	O
)	O
on	O
,	O
(	O
rho	O
)	O
on	O
,	O
(	O
base	O
value	O
)	O
on	O
,	O
(	O
eNcode	O
)	O
on	O
,	O
(	O
modulus	O
)	O
on	O
and	O
so	O
on	O
.	O
</s>
<s>
This	O
makes	O
it	O
easier	O
for	O
an	O
English-language	O
speaker	O
to	O
type	O
APL	B-Language
on	O
a	O
non-APL	O
keyboard	O
,	O
providing	O
one	O
has	O
visual	O
feedback	O
on	O
one	O
's	O
screen	O
.	O
</s>
<s>
Later	O
IBM	O
terminals	O
,	O
notably	O
the	O
IBM	B-Operating_System
3270	I-Operating_System
display	O
stations	O
,	O
had	O
an	O
alternate	O
keyboard	O
arrangement	O
which	O
is	O
the	O
basis	O
for	O
some	O
of	O
the	O
modern	O
APL	B-Language
keyboard	O
layouts	O
in	O
use	O
today	O
.	O
</s>
<s>
Further	O
APL	B-Language
characters	O
were	O
available	O
by	O
overstriking	B-Application
one	O
character	O
with	O
another	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
log	O
symbol	O
( ⍟	O
)	O
was	O
formed	O
by	O
overstriking	B-Application
with	O
.	O
</s>
<s>
New	O
overstrikes	B-Application
were	O
introduced	O
by	O
vendors	O
as	O
they	O
produced	O
versions	O
of	O
APL	B-Language
tailored	O
to	O
specific	O
hardware	O
,	O
system	O
features	O
,	O
file	O
systems	O
,	O
and	O
so	O
on	O
.	O
</s>
<s>
Further	O
,	O
printing	O
terminals	O
and	O
early	O
APL	B-Language
cathode-ray	O
terminals	O
were	O
able	O
to	O
display	O
arbitrary	O
overstrikes	B-Application
,	O
but	O
as	O
personal	O
computers	O
rapidly	O
replaced	O
terminals	O
as	O
a	O
data-entry	O
device	O
,	O
APL	B-Language
character	O
support	O
became	O
provided	O
as	O
an	O
APL	B-Language
Character	O
Generator	O
ROM	O
or	O
a	O
soft	O
character	O
set	O
rendered	O
by	O
the	O
display	O
device	O
.	O
</s>
<s>
With	O
the	O
advent	O
of	O
the	O
modern	O
PC	O
,	O
APL	B-Language
characters	O
were	O
defined	O
in	O
specific	O
fonts	O
,	O
eliminating	O
the	O
distinction	O
between	O
overstruck	O
characters	O
and	O
standard	O
characters	O
.	O
</s>
