& entity

[Robert Frost-Bridges]

Does a parser or processing application not work through a document one
character at a time starting from the first?

I have begun reading up on xml and note that in certain circumstances &
is to be escaped with & just as I have often done when writing html.
How is it that & can confuse but & is ok when the first character of
the entity is the one being escaped?

 

[Jukka K. Korpela]

Does a parser or processing application not work through a document one
character at a time starting from the first?

Not necessarily. There is not prohibition against parallel processing.

I have begun reading up on xml and note that in certain circumstances &
is to be escaped with & just as I have often done when writing html.

XML, the strongly simplified form of SGML, makes it mandatory to "escape"
& as & in all contexts, when it is meant to be a data character.
(Triviality is progress. War is peace.) Ref.:
http://www.w3.org/TR/REC-xml#syntax

How is it that & can confuse but & is ok when the first character of
the entity is the one being escaped?

The character & does not confuse. It indicates the start of an entity
reference or a character reference in certain contexts by SGML rules.
XML simplifies this.

 

[Toby A Inkster]

How is it that & can confuse but & is ok when the first character of
the entity is the one being escaped?

'&' *always* means 'this is the start of an entity' in XML. There is no
room for confusion.

 

[Robert Frost-Bridges]

[Robert Frost-Bridges]
Does a parser or processing application not work through a document one
character at a time starting from the first?

Not necessarily. There is not prohibition against parallel processing.

Or an out and out guess - on reading about how character encoding may
deduced in the document linked in your post,
http://www.w3.org/TR/REC-xml#sec-guessing

which has a rather appropriate uri.

 

[Robert Frost-Bridges]

'&' *always* means 'this is the start of an entity' in XML. There is no
room for confusion.

Which is what I didn't quite get, 'til this thread. If I type red&blue
it will throw up an error because there is no entity &blue.

It's all clear to me now