Web Client Programming with Perl Automating Tasks on the Web By Clinton Wong 1st Edition March 1997 This book is out of print, but it has been made available online through the O'Reilly Open Books Project.

Appendix B
Reference Tables

This appendix contains several tables that will be useful when negotiating HTTP content. Covered in this appendix are:

Media Types

Whenever an entity-body is sent via HTTP, a media type must be sent using the Content-type header. Also, web clients can use the Accept header to define which media types the client can handle.

Character Encoding

In URL-encoded data (as described in Chapter 3, Learning HTTP), any "special" characters such as spaces and punctuation must be encoded with a % escape sequence.

Languages

Entity-bodies can be sent with a Content-language header, to declare what language the entity is written in. Clients can declare which languages they can handle, using the Accept-language header.

Character Sets

Clients can use the Accept-charset header to declare which character sets they are capable of handling.

Media Types

Listed below are media types that are registered with the Internet Assigned Number Authority (IANA). According to the HTTP specification, use of nonregistered media types is discouraged.

The IANA media list is available in RFC 1700. A more readable document describing the assigned media types is available at ftp://ftp.isi.edu/in-notes/iana/assignments/media-types/.

A variety of methods is used to identify the media type of a document. The easiest method, but the least accurate, is to map well-known file extensions with a media type. For example, a file that ends in ".GIF" would map to "image/gif". However, in usual practice, there is no verification that the file is in fact a GIF file.

A more accurate method would examine the structure or data format of the file and map it to a media type. For some media types, magic numbers allow this to happen. For example, all GIF files begin with the three uppercase letters of GIF, and all JPEG files begin with 0xFFD8 (hexadecimal notation). This method, however, is more time consuming.

Under some filesystems, media types may be mapped by examining the file type/creator attribute of the file. While this is easily achieved under MacOS's HFS, other filesystems (DOS, NTFS, BSD) do not have these file attributes.

Table B-1: Internet Media Types

Type	Subtype
text	plain
text	richtext
text	enriched
text	tab-separated-values
text	html
text	sgml
multipart	mixed
multipart	alternative
multipart	digest
multipart	parallel
multipart	appledouble
multipart	header-set
multipart	form-data
multipart	related
multipart	report
multipart	voice-message
message	rfc822
message	partial
message	external-body
message	news
message	http
application	octet-stream
application	postscript
application	oda
application	atomicmail
application	andrew-inset
application	slate
application	wita
application	dec-dx
application	dca-rft
application	activemessage
application	rtf
application	applefile
application	mac-binhex40
application	news-message-id
application	news-transmission
application	wordperfect5.1
application	pdf
application	zip
application	macwriteii
application	msword
application	remote-printing
application	mathematica
application	cybercash
application	commonground
application	iges
application	riscos
application	eshop
application	x400-bp
application	sgml
application	cals-1840
application	vnd.framemaker
application	vnd.mif
application	vnd.ms-excel
application	vnd.ms-powerpoint
application	vnd.ms-project
application	vnd.ms-works
application	vnd.ms-tnef
application	vnd.svd
application	vnd.music-niff
application	vnd.ms-artgalry
application	vnd.truedoc
application	vnd.koan
image	jpeg
image	gif
image	ief
image	g3fax
image	tiff
image	cgm
image	naplps
image	vnd.dwg
image	vnd.svf
image	vnd.dxf
audio	basic
audio	32kadpcm
video	mpeg
video	quicktime
video	vnd.vivo

Character Encoding

When the client sends data to a CGI program using the Content-type of application/x-www-form-urlencoded, certain special characters are encoded to eliminate ambiguity. Table B-2 shows which characters are transformed and which are not transformed. For more information on URLs, see RFC 1738.

Table B-2: Character Encoding

ASCII	Symbol	CGI representation
< 32		always encode with %xx where xx is the hexadecimal representation of the character
32		+ or %20
33	!	%21
34	"	%22
35	#	%23
36	$	%24
37	%	%25
38	&	%26
39	'	%27
40	(	%28
41	)	%29
42	*	*
43	+	%2B
44	,	%2C
45	-	-
46	.	.
47	/	%2F
48	0	0
49	1	1
50	2	2
51	3	3
52	4	4
53	5	5
54	6	6
55	7	7
56	8	8
57	9	9
58	:	%3A
59	;	%3B
60	<	%3C
61	=	%3D
62	>	%3E
63	?	%3F
64	@	%40
65	A	A
66	B	B
67	C	C
68	D	D
69	E	E
70	F	F
71	G	G
72	H	H
73	I	I
74	J	J
75	K	K
76	L	L
77	M	M
78	N	N
79	O	O
80	P	P
81	Q	Q
82	R	R
83	S	S
84	T	T
85	U	U
86	V	V
87	W	W
88	X	X
89	Y	Y
90	Z	Z
91	[	%5B
92	\	%5C
93	]	%5D
94	^	%5E
95	_	_
96	`	%60
97	a	a
98	b	b
99	c	c
100	d	d
101	e	e
102	f	f
103	g	g
104	h	h
105	i	i
106	j	j
107	k	k
108	l	l
109	m	m
110	n	n
111	o	o
112	p	p
113	q	q
114	r	r
115	s	s
116	t	t
117	u	u
118	v	v
119	w	w
120	x	x
121	y	y
122	z	z
123	{	%7B
124	|	%7C
125	}	%7D
126	~	%7E
127		%7F
> 127		always encode with %xx where xx is the hexadecimal representation of the character

Languages

A language tag is of the form of:

<primary-tag> <-subtag>

where zero or more subtags are allowed. The primary-tag specifies the language, and the subtag specifies parameters to the language, like dialect information, country identification, or script variations. RFC 1766 contains the complete documentation of languages and parameter usage. The key values for the primary-tag and subtag are outlined in Tables B-3 and B-4, respectively.

Examples:

de

(German)

en

(English)

en-us

(English, USA)

Table B-3 lists the primary langauge tags as defined in ISO 639 and RFC 1766.

Table B-3: Primary Language Types

Primary Tag	Language
aa	Afar
ab	Abkhazian
af	Afrikaans
am	Amharic
ar	Arabic
as	Assamese
ay	Aymara
az	Azerbaijani
ba	Bashkir
be	Byelorussian
bg	Bulgarian
bh	Bihari
bi	Bislama
bn	Bengali; Bangla
bo	Tibetan
br	Breton
ca	Catalan
co	Corsican
cs	Czech
cy	Welsh
da	Danish
de	German
dz	Bhutani
el	Greek
en	English
eo	Esperanto
es	Spanish
et	Estonian
eu	Basque
fa	Persian
fi	Finnish
fj	Fiji
fo	Faeroese
fr	French
fy	Frisian
ga	Irish
gd	Scots, Gaelic
gl	Galician
gn	Guarani
gu	Gujarati
ha	Hausa
he	Hebrew
hi	Hindi
hr	Croatian
hu	Hungarian
hy	Armenian
ia	Interlingua
id	Indonesian
ie	Interlingue
ik	Inupiak
is	Icelandic
it	Italian
iu	Inuktitat
iw	Hebrew
ja	Japanese
jw	Javanese
ka	Georgian
kk	Kazakh
kl	Greenlandic
km	Cambodian
kn	Kannada
ko	Korean
ks	Kashmiri
ku	Kurdish
ky	Kirghiz
la	Latin
ln	Lingala
lo	Laothian
lt	Lithuanian
lv	Latvian, Lettish
mg	Malagasy
mi	Maori
mk	Macedonian
ml	Malayalam
mn	Mongolian
mo	Moldavian
mr	Marathi
ms	Malay
mt	Maltese
my	Burmese
na	Nauru
ne	Nepali
nl	Dutch
no	Norwegian
oc	Occitan
om	(Afan) Oromo
or	Oriya
pa	Punjabi
pl	Polish
ps	Pashto, Pushto
pt	Portuguese
qu	Quechua
rm	Rhaeto-Romance
rn	Kirundi
ro	Romanian
ru	Russian
rw	Kinyarwanda
sa	Sanskrit
sd	Sindhi
sg	Sangro
sh	Serbo-Croatian
si	Singhalese
sk	Slovak
sl	Slovenian
sm	Samoan
sn	Shona
so	Somali
sq	Albanian
sr	Serbian
ss	Siswati
st	Sesotho
su	Sudanese
sv	Swedish
sw	Swahili
ta	Tamil
te	Tegulu
tg	Tajik
th	Thai
ti	Tigrinya
tk	Turkmen
tl	Tagalog
tn	Setswana
to	Tonga
tr	Turkish
ts	Tsonga
tt	Tatar
tw	Twi
ug	Uigar
uk	Ukrainian
ur	Urdu
uz	Uzbek
vi	Vietnamese
vo	Volapuk
wo	Wolof
xh	Xhosa
yi	Yiddish
yo	Yoruba
za	Zhuang
zh	Chinese
zu	Zulu

Table B-4 lists the language subtypes as defined in ISO 3166.

Table B-4: Language Subtypes

Subtype	Country
AD	Andorra
AE	United Arab Emirates
AF	Afghanistan
AG	Antigua and Barbuda
AI	Anguilla
AL	Albania
AM	Armenia
AN	Netherland Antilles
AO	Angola
AQ	Antarctica
AR	Argentina
AS	American Samoa
AT	Austria
AU	Australia
AW	Aruba
AZ	Azerbaidjan
BA	Bosnia-Herzegovina
BB	Barbados
BD	Bangladesh
BE	Belgium
BF	Burkina Faso
BG	Bulgaria
BH	Bahrain
BI	Burundi
BJ	Benin
BM	Bermuda
BN	Brunei Darussalam
BO	Bolivia
BR	Brazil
BS	Bahamas
BT	Buthan
BV	Bouvet Island
BW	Botswana
BY	Belarus
BZ	Belize
CA	Canada
CC	Cocos (Keeling) Isl.
CF	Central African Rep.
CG	Congo
CH	Switzerland
CI	Ivory Coast
CK	Cook Islands
CL	Chile
CM	Cameroon
CN	China
CO	Colombia
CR	Costa Rica
CS	Czechoslovakia
CU	Cuba
CV	Cape Verde
CX	Christmas Island
CY	Cyprus
CZ	Czech Republic
DE	Germany
DJ	Djibouti
DK	Denmark
DM	Dominica
DO	Dominican Republic
DZ	Algeria
EC	Ecuador
EE	Estonia
EG	Egypt
EH	Western Sahara
ES	Spain
ET	Ethiopia
FI	Finland
FJ	Fiji
FK	Falkland Isl. (Malvinas)
FM	Micronesia
FO	Faroe Islands
FR	France
FX	France (European Ter.)
GA	Gabon
GB	Great Britain (UK)
GD	Grenada
GE	Georgia
GH	Ghana
GI	Gibraltar
GL	Greenland
GP	Guadeloupe (Fr.)
GQ	Equatorial Guinea
GF	Guyana (Fr.)
GM	Gambia
GN	Guinea
GR	Greece
GT	Guatemala
GU	Guam (US)
GW	Guinea Bissau
GY	Guyana
HK	Hong Kong
HM	Heard & McDonald Isl.
HN	Honduras
HR	Croatia
HT	Haiti
HU	Hungary
ID	Indonesia
IE	Ireland
IL	Israel
IN	India
IO	British Indian O. Terr.
IQ	Iraq
IR	Iran
IS	Iceland
IT	Italy
JM	Jamaica
JO	Jordan
JP	Japan
KE	Kenya
KG	Kirgistan
KH	Cambodia
KI	Kiribati
KM	Comoros
KN	St. Kitts Nevis Anguilla
KP	Korea (North)
KR	Korea (South)
KW	Kuwait
KY	Cayman Islands
KZ	Kazachstan
LA	Laos
LB	Lebanon
LC	Saint Lucia
LI	Liechtenstein
LK	Sri Lanka
LR	Liberia
LS	Lesotho
LT	Lithuania
LU	Luxembourg
LV	Latvia
LY	Libya
MA	Morocco
MC	Monaco
MD	Moldavia
MG	Madagascar
MH	Marshall Islands
ML	Mali
MM	Myanmar
MN	Mongolia
MO	Macau
MP	Northern Mariana Isl.
MQ	Martinique (Fr.)
MR	Mauritania
MS	Montserrat
MT	Malta
MU	Mauritius
MV	Maldives
MW	Malawi
MX	Mexico
MY	Malaysia
MZ	Mozambique
NA	Namibia
NC	New Caledonia (Fr.)
NE	Niger
NF	Norfolk Island
NG	Nigeria
NI	Nicaragua
NL	Netherlands
NO	Norway
NP	Nepal
NR	Nauru
NT	Neutral Zone
NU	Niue
NZ	New Zealand
OM	Oman
PA	Panama
PE	Peru
PF	Polynesia (Fr.)
PG	Papua New Guinea
PH	Philippines
PK	Pakistan
PL	Poland
PM	St. Pierre & Miquelon
PN	Pitcairn
PT	Portugal
PR	Puerto Rico (US)
PW	Palau
PY	Paraguay
QA	Qatar
RE	Reunion (Fr.)
RO	Romania
RU	Russian Federation
RW	Rwanda
SA	Saudi Arabia
SB	Solomon Islands
SC	Seychelles
SD	Sudan
SE	Sweden
SG	Singapore
SH	St. Helena
SI	Slovenia
SJ	Svalbard & Jan Mayen Isl.
SK	Slovak Republic
SL	Sierra Leone
SM	San Marino
SN	Senegal
SO	Somalia
SR	Suriname
ST	St. Tome and Principe
SU	Soviet Union
SV	El Salvador
SY	Syria
SZ	Swaziland
TC	Turks & Caicos Islands
TD	Chad
TF	French Southern Terr.
TG	Togo
TH	Thailand
TJ	Tadjikistan
TK	Tokelau
TM	Turkmenistan
TN	Tunisia
TO	Tonga
TP	East Timor
TR	Turkey
TT	Trinidad & Tobago
TV	Tuvalu
TW	Taiwan
TZ	Tanzania
UA	Ukraine
UG	Uganda
UK	United Kingdom
UM	US Minor Outlying Isl.
US	United States
UY	Uruguay
UZ	Uzbekistan
VA	Vatican City State
VC	St.Vincent & Grenadines
VE	Venezuela
VG	Virgin Islands (British)
VI	Virgin Islands (US)
VN	Vietnam
VU	Vanuatu
WF	Wallis & Futuna Islands
WS	Samoa
YE	Yemen
YU	Yugoslavia
ZA	South
ZM	Zambia
ZR	Zaire
ZW	Zimbabwe

Character Sets

Table B-5 lists the character sets that may be used with the Accept-language and Content-language HTTP headers. This list does not describe all of the possible character sets of international languages that can appear in the headers. For a comprehensive list of character sets, their aliases, and pointers to more descriptive documents, refer to RFC 1700.

Table B-5: Character Sets

Character Sets	Language	Source
US-ASCII	American Standard Code for Information Exchange	RFC 1345
ISO-8859-1	Latin Alphabet No. 1	RFC 1345
ISO-8859-2	Latin Alphabet No. 2	RFC 1345
ISO-8859-3	Latin Alphabet No. 3	RFC 1345
ISO-8859-4	Latin Alphabet No. 4	RFC 1345
ISO-8859-5	Latin/Cyrillic Alphabet	RFC 1345
ISO-8859-6	Latin/Arabic Alphabet	RFC 1345
ISO-8859-7	Latin/Greek Alphabet	RFC 1345
ISO-8859-8	Latin/Hebrew Alphabet	RFC 1345
ISO-8859-9	Latin Alphabet No. 5	RFC 1345
ISO-2022-JP	Japanese	RFC 1468
ISO-2022-JP-2	Extension of Japanese in ISO-2022-JP	RFC 1554
ISO-2022-KR	Korean	RFC 1557
UNICODE-1-1	Unicode for MIME	RFC 1641
UNICODE-1-1-UTF-7	7-bit UCS Transformation Format	RFC 1642
UNICODE-1-1-UTF-8	8-bit UCS Transformation Format	N/A

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