Handleiding Kompozer 07 (pagina 50 van 58) (Engels)

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KompoZer User Guide — 17 December 2007 Based on version 0.7.10 50

Note A font list lists fonts the first of which will

be used if available. It does not check that the

character required is supported by the font. So

even if support is provided by a font lower in the

list that may not be accessed.

Check the rendering of a page on as many different

browsers as possible. Mozilla browsers do authors only

a partial service since, if a character is encountered

which is not included in the font(s) listed they will make

an attempt to find the character on other fonts in-

stalled on the machine. Authors should however check

all pages using MSIE 6 which does not offer this

capability. (MSIE7 will substitute for a few characters.)

Visitors may finish up looking at square boxes instead

of the character required.

Alan Wood offers several pages which are extremely

useful in this respect. “Using special characters from

Windows Glyph List 4 (WGL4) in HTML” [Ref 3] lists

characters in the WGL4 set and which are likely to be

widely available. “Unicode fonts for Windows comput-

ers” [Ref 4] lists which fonts carry specific ranges of

Unicode characters and, more interestingly, shows

distribution of the fonts so that authors may check

likely availability to visitors. Those wishing to use a

rarer character may check which fonts include them at

Unicode character ranges and the Unicode fonts that

support them [Ref 5].

A6.3.8.2 Examples

While preparing this page, for instance, Table A6.3-

1 displayed correctly in Firefox and KompoZer but in

MSIE the arrows originally appeared as squares. The

issue is reproduced in the box.

Example

Character U+21D1 not included any font used from

the list specified (Tahoma, Arial, Helvetica, sans-serif).

The arrow appears as a square when using MSIE = 7

Same demonstration but set up spanning the arrow

with font-family: ‘Lucida Sans Unicode’ .

The arrows use comparatively rare characters that

do not appear in the Tahoma font used but, on the

writer's machine at least, the Gecko engine was able to

retrieve them, possibly from Lucida Sans Unicode.

The result is that visitors using MSIE see boxes

instead of arrows but those using Firefox or Opera may

see the arrows if Lucida Sans Unicode or some other

font with the characters is installed on their machine.

A work-around this issue is possible, as also shown

in the box. The list specifying the font is modified so

that the first in the list becomes 'Lucida Sans Unicode'.

If this is available it will be used, otherwise the choice

passes down the list. Alan Wood shows that this font is

supplied with Windows XP and Windows 2000 which

cover 90% of installations (mid 2007).

This is a moderately, but not very, robust solution.

Had the availability of the arrows been critical to un-

derstanding the table it would have been necessary to

change the design.

While the arrows may be considered rare and unu-

sual characters even characters covered by some ISO-

8859 options may not be reliable. In viewing Table

A6.3-2, depending on the browser in use and fonts

installed there are two characters, Drachma sign (Code

A5) and Greek ypogegrammeni (Code AA), which may

not display correctly. In cases like these checking the

WGL4 list may provide a warning because neither of

the characters is listed.

A6.4 Special characters

A6.4.1 Entities or numeric character references

A6.4.1.1 Output the following characters

The way in which characters are coded in the

source for the page may be altered in KompoZer using

Tools > Preferences > Advanced. In the Special Charac-

ters area there are four options under ‘Output the

following characters as entities’

Only & < > and non-breakable whitespace

The above and Latin-1 letters

HTML 4 special characters

Use &#...; notation for all non-ASCII characters

The options refer to characters typed onto the page

which will be readable by a visitor to a site. Irrespective

of the option set the visual appearance on screen will

remain the same.

First option

‘Only & < > and non-breakable whitespace’

Note In normal practice the character referred to

as ‘non-breakable whitespace.’ is called ‘no-

break space.’ (entity  ).

The section on 'Preferences' recommends this as the

preferred option.

This is the minimal setting. The characters listed

must always be encoded whatever option is selected.

With this selection the encoding will be as entities.

Since the character < occurs in HTML code to mark the

start of an element, if it is included in the page text the

browser would expect to to start a new element and the

page would become corrupted. It must always be en-

coded. The > character marks the end of an element

and should be safe to use but W3C recommend that it

also be encoded since it may confuse older browsers

See section 5.3.2 of the HTML Specification [Ref 16]. If

you wish to override this check the box . ‘Don’t encode

> outside of attribute values’.

Since entities and numeric character references

start with an ampersand (&) a similar problem occurs

with this character.

Outputing the no-break space as an entity is con-

venient since it would otherwise look like a normal

space in a listing.

With this option the output will be an entity where

specified, else for encodable characters, it will be the

code for the character else the character will be output

as a decimal numeric character code.

Before publishing a page always select this option

since it will result in the smallest file size.

Second option

The option ‘The above and Latin-1 letters’ Strictly

should read 'The above and Latin-1 characters except

ASCII characters'. That refers to characters in the

Latin-1 set with codes in the range A0 to FF.

The output code for ASCII characters is the charac-

ter code, for the remaining Latin-1 characters is the

entity, else is a decimal numeric character reference.

Third option

The option ‘HTML 4 special characters’ refers to

all characters for which The HTML 4 specification [Ref

16] (Section 24) provides an entity reference.

Kompozer 07 Handleiding

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