Acorn Browse HTML Support

1. Document Status
2. Issue / Revision History

3. Supported Elements
4. Supported Entites
5. Supported Colours
6. Broken HTML

7. Further reading
   1. HTML 4.0 Specification
   2. Acorn Browse Plug-In Handling Description

The browser's parser recognises the following set of elements and the browser itself will act on the following element attributes:

Footnotes from the above table:

1. Alignment - Browse does not support floating objects, so text cannot flow around images and navigation tables cannot float next to content tables for example. It will attempt to at least align objects centred or to the left or right margin where possible. See [4] also.
2. Unsupported - The browser does nothing with this element.
3. META - only used for client pull presently.
4. UK English - for some common items Browse will recognise UK and 'American English' spellings, e.g. "color" and "colour", "center" and "centre".
5. Partial support - Some values may not work as expected (typically alignment specification).
6. Internal URLs - Navigator (but not MSIE) knows certain "magic" URLs such as 'internal-gopher-image'. Web proxies have been known to pass these out to people using FTP through them. Browse does not support these magic values.

The full range of HTML 4 entities are supported.

Name	Entity	Unicode	Name	Entity	Unicode	Name	Entity	Unicode
Æ	Æ	00C6	Á	Á	00C1	Â	Â	00C2
À	À	00C0	Α	Α	0391	Å	Å	00C5
Ã	Ã	00C3	Ä	Ä	00C4	Β	Β	0392
Ç	Ç	00C7	Χ	Χ	03A7	‡	‡	2021
Δ	Δ	0394	Ð	Ð	00D0	É	É	00C9
Ê	Ê	00CA	È	È	00C8	Ε	Ε	0395
Η	Η	0397	Ë	Ë	00CB	Γ	Γ	0393
Í	Í	00CD	Î	Î	00CE	Ì	Ì	00CC
Ι	Ι	0399	Ï	Ï	00CF	Κ	Κ	039A
Λ	Λ	039B	Μ	Μ	039C	Ñ	Ñ	00D1
Ν	Ν	039D	Œ	Œ	0152	Ó	Ó	00D3
Ô	Ô	00D4	Ò	Ò	00D2	Ω	Ω	03A9
Ο	Ο	039F	Ø	Ø	00D8	Õ	Õ	00D5
Ö	Ö	00D6	Φ	Φ	03A6	Π	Π	03A0
″	″	2033	Ψ	Ψ	03A8	Ρ	Ρ	03A1
Š	Š	0160	Σ	Σ	03A3	Þ	Þ	00DE
Τ	Τ	03A4	Θ	Θ	0398	Ú	Ú	00DA
Û	Û	00DB	Ù	Ù	00D9	Υ	Υ	03A5
Ü	Ü	00DC	Ξ	Ξ	039E	Ý	Ý	00DD
Ÿ	Ÿ	0178	Ζ	Ζ	0396	á	á	00E1
â	â	00E2	´	´	00B4	æ	æ	00E6
à	à	00E0	ℵ	ℵ	2135	α	α	03B1
&	&	0026	∧	∧	2227	∠	∠	2220
å	å	00E5	≈	≈	2248	ã	ã	00E3
ä	ä	00E4	„	„	201E	β	β	03B2
¦	¦	00A6	•	•	2022	∩	∩	2229
ç	ç	00E7	¸	¸	00B8	¢	¢	00A2
χ	χ	03C7	ˆ	ˆ	02C6	♣	♣	2663
≅	≅	2245	©	©	00A9	↵	↵	21B5
∪	∪	222A	¤	¤	00A4	⇓	⇓	21D3
†	†	2020	↓	↓	2193	°	°	00B0
δ	δ	03B4	♦	♦	2666	÷	÷	00F7
é	é	00E9	ê	ê	00EA	è	è	00E8
∅	∅	2205	 		2003	 		2002
ε	ε	03B5	≡	≡	2261	η	η	03B7
ð	ð	00F0	ë	ë	00EB	€	€	20AC
∃	∃	2203	ƒ	ƒ	0192	∀	∀	2200
½	½	00BD	¼	¼	00BC	¾	¾	00BE
⁄	⁄	2044	γ	γ	03B3	≥	≥	2265
>		003E	⇔	⇔	21D4	↔	↔	2194
♥	♥	2665	…	…	2026	í	í	00ED
î	î	00EE	¡	¡	00A1	ì	ì	00EC
ℑ	ℑ	2111	∞	∞	221E	∫	∫	222B
ι	ι	03B9	¿	¿	00BF	∈	∈	2208
ï	ï	00EF	κ	κ	03BA	⇐	⇐	21D0
λ	λ	03BB	⟨	⟨	2329	«	«	00AB
←	←	2190	⌈	⌈	2308	“	“	201C
≤	≤	2264	⌊	⌊	230A	∗	∗	2217
◊	◊	25CA	‎	‎	200E	‹	‹	2039
‘	‘	2018	<		003C	¯	¯	00AF
—	—	2014	µ	µ	00B5	·	·	00B7
−	−	2212	μ	μ	03BC	∇	∇	2207
 		00A0	–	–	2013	≠	≠	2260
∋	∋	220B	¬	¬	00AC	∉	∉	2209
⊄	⊄	2284	ñ	ñ	00F1	ν	ν	03BD
ó	ó	00F3	ô	ô	00F4	œ	œ	0153
ò	ò	00F2	‾	‾	203E	ω	ω	03C9
ο	ο	03BF	⊕	⊕	2295	∨	∨	2228
ª	ª	00AA	º	º	00BA	ø	ø	00F8
õ	õ	00F5	⊗	⊗	2297	ö	ö	00F6
¶	¶	00B6	∂	∂	2202	‰	‰	2030
⊥	⊥	22A5	φ	φ	03C6	π	π	03C0
ϖ	ϖ	03D6	±	±	00B1	£	£	00A3
′	′	2032	∏	∏	220F	∝	∝	221D
ψ	ψ	03C8	"	"	0022	⇒	⇒	21D2
√	√	221A	⟩	⟩	232A	»	»	00BB
→	→	2192	⌉	⌉	2309	”	”	201D
ℜ	ℜ	211C	®	®	00AE	⌋	⌋	230B
ρ	ρ	03C1	‏	‏	200F	›	›	203A
’	’	2019	‚	‚	201A	š	š	0161
⋅	⋅	22C5	§	§	00A7	­	­	00AD
σ	σ	03C3	ς	ς	03C2	∼	∼	223C
♠	♠	2660	⊂	⊂	2282	⊆	⊆	2286
∑	∑	2211	⊃	⊃	2283	¹	¹	00B9
²	²	00B2	³	³	00B3	⊇	⊇	2287
ß	ß	00DF	τ	τ	03C4	∴	∴	2234
θ	θ	03B8	ϑ	ϑ	03D1	 		2009
þ	þ	00FE	˜	˜	02DC	×	×	00D7
™	™	2122	⇑	⇑	21D1	ú	ú	00FA
↑	↑	2191	û	û	00FB	ù	ù	00F9
¨	¨	00A8	ϒ	ϒ	03D2	υ	υ	03C5
ü	ü	00FC	℘	℘	2118	ξ	ξ	03BE
ý	ý	00FD	¥	¥	00A5	ÿ	ÿ	00FF
ζ	ζ	03B6	‍	‍	200D	‌	‌	200C

Name	R	G	B	Name	R	G	B
aliceblue	f0	f8	ff	antiquewhite	fa	eb	d7
aqua	00	ff	ff	aquamarine	7f	ff	d4
azure	f0	ff	ff	beige	f5	f5	dc
bisque	ff	e4	c4	black	00	00	00
blanchedalmond	ff	eb	cd	blue	00	00	ff
blueviolet	8a	2b	e2	brown	a5	2a	2a
burlywood	de	b8	87	cadetblue	5f	9e	a0
chartreuse	7f	ff	00	chocolate	d2	69	1e
coral	ff	7f	50	cornflowerblue	64	95	ed
cornsilk	ff	f8	dc	crimson	dc	14	3c
cyan	00	ff	ff	darkblue	00	00	8b
darkcyan	00	8b	8b	darkgoldenrod	b8	86	0b
darkgray	a9	a9	a9	darkgreen	00	64	00
darkkhaki	bd	b7	6b	darkmagenta	8b	00	8b
darkolivegreen	55	6b	2f	darkorange	ff	8c	00
darkorchid	99	32	cc	darkred	8b	00	00
darksalmon	e9	96	7a	darkseagreen	8d	bc	8f
darkslateblue	48	3d	8b	darkslategray	2f	4f	4f
darkturquoise	00	ce	d1	darkviolet	94	00	d3
deeppink	ff	14	93	deepskyblue	00	bf	ff
dimgray	69	69	69	dodgerblue	1e	90	ff
firebrick	b2	22	22	floralwhite	ff	fa	f0
forestgreen	22	8b	22	fuchsia	ff	00	ff
gainsboro	dc	dc	dc	ghostwhite	f8	f8	ff
gold	ff	d7	00	goldenrod	da	a5	20
gray	80	80	80	green	00	80	00
greenyellow	ad	ff	2f	honeydew	f0	ff	f0
hotpink	ff	69	b4	indianred	cd	5c	5c
indigo	4b	00	82	ivory	ff	ff	f0
khaki	f0	e6	8c	lavender	e6	e6	fa
lavenderblush	ff	f0	f5	lawngreen	7c	fc	00
lemonchiffon	ff	fa	cd	lightblue	ad	d8	e6
lightcoral	f0	80	80	lightcyan	e0	ff	ff
lightgoldenrodyellow	fa	fa	d2	lightgreen	90	ee	90
lightgrey	d3	d3	d3	lightpink	ff	b6	c1
lightsalmon	ff	a0	7a	lightseagreen	20	b2	aa
lightskyblue	87	ce	fa	lightslategray	77	88	99
lightsteelblue	b0	c4	de	lightyellow	ff	ff	e0
lime	00	ff	00	limegreen	32	cd	32
linen	fa	f0	e6	magenta	ff	00	ff
maroon	80	00	00	mediumaquamarine	66	cd	aa
mediumblue	00	00	cd	mediumorchid	ba	55	d3
mediumpurple	93	70	db	mediumseagreen	3c	b3	71
mediumslateblue	7b	68	ee	mediumspringgreen	00	fa	9a
mediumturquoise	48	d1	cc	mediumvioletred	c7	15	85
midnightblue	19	19	70	mintcream	f5	ff	fa
mistyrose	ff	e4	e1	moccasin	ff	e4	b5
navajowhite	ff	de	ad	navy	00	00	80
oldlace	fd	f5	e6	olive	80	80	00
olivedrab	6b	8e	23	orange	ff	a5	00
orangered	ff	45	00	orchid	da	70	d6
palegoldenrod	ee	e8	aa	palegreen	98	fb	98
paleturquoise	af	ee	ee	palevioletred	db	70	93
papayawhip	ff	ef	d5	peachpuff	ff	da	b9
peru	cd	85	3f	pink	ff	c0	cb
plum	dd	a0	dd	powderblue	b0	e0	e6
purple	80	00	80	red	ff	00	00
rosybrown	bc	8f	8f	royalblue	41	69	e1
saddlebrown	8b	45	13	salmon	fa	80	72
sandybrown	f4	a4	60	seagreen	2e	8b	57
seashell	ff	f5	ee	sienna	a0	52	2d
silver	c0	c0	c0	skyblue	87	ce	eb
slateblue	6a	5a	cd	slategray	70	80	90
snow	ff	fa	fa	springgreen	00	ff	7f
steelblue	46	82	b4	tan	d2	b4	8c
teal	00	80	80	thistle	d8	bf	d8
tomato	ff	63	47	turquoise	40	e0	d0
violet	ee	82	ee	wheat	f5	de	b3
white	ff	ff	ff	whitesmoke	f5	f5	f5
yellow	ff	ff	00	yellowgreen	9a	cd	32

The browser will cope with a variety of types of broken HTML, not least of which includes incorrect structure (documents with TITLE inside BODY sections and so-forth). The measures detailed below have been arrived at over a lengthy development cycle where behaviour of Navigator, Internet Explorer, and other browsers is compared on various sites which failed in Browse. Over time, the parser and browser have become progressively more robust to broken HTML, though there is always work to do to improve this.

Steps taken include:

• Entities - progressive matching is used so that when semi-colons are missed off the end of entity names, a good chance of finding the right match is made (if no match is found the entire entity including the '&' is displayed).

• Comments - '' end a comment sequence, with matching angle bracket pairs counted in between. Comment handling is usually in a state of flux as the parser cannot currently do a relaxed match, waiting until the end of the document, then track back and do a strict match to '-->' as in, say, Navigator. This means that not all cases of broken comments that would manage to work in Navigator will work in Browse.

• Mismatched quotes - Single and double quote marks are allowed for attribute values, and missing quotes are acceptable. A missing opening quote is also survived, as are multiple consecutive quotes to close attributes values. In a similar manner to comment handling, a missing closing quote is fatal because the parser cannot backtrack and clean up afterwards.

• Colour names - All spaces inside colour names are collapsed, so whether people write "dark red" or "d A r K R e D", the correct result is obtained. If a named colour is not found, the value is checked to see if it is legal hex - if so, this is used instead (so the '#' may be missed off). In addition, hex values specified explicitly with '#' may contain the letter O instead of zero. To avoid collapsing all colours to the same value (e.g. particularly foreground or background colours), a random colour choice is used if the colour name is not recognised despite all of the above mechanisms. Note that the greyscale extended colour names (e.g. "grey20", "grey40") are not supported at present.

• Frame specifiers - Rubbish in "cols" or "rows" attributes values is stripped, so values such as "30 pixels, *, 100 %, 50px" is handled gracefully.

• Common unusual constructs - Certain cases are specifically hard-coded for, e.g.

• ... means put a paragraph before both the bullet point and associated line of text, rather than between the bullet point and text.

HTML 4.0 Specification

The "horse's mouth" description of current HTML at the time of writing.

Acorn Browse Plug-In Handling Description

A description of the way that the browser invokes plug-ins.

Last updated 5 October 1998 © Acorn Computers Limited, 1997