T
Tom Anderson
Hi all,
I can see from the XML spec what processing instructions and notations
are, syntactically. I even just about understand how notations relate to
external entities. But i don't understand what you'd actually use them for
in practice!
The one example i've found is using an xml-stylesheet PI to specify a
stylesheet. Are there others?
How about notations and external entities? Is the idea that they're a
mechanism of linkage to external files that's more concrete than just
using a URL? So, if i was writing a bizarro world HTML, i could specify
images like this in the DTD:
<!NOTATION jpeg SYSTEM "http://some-kind-of-URL">
<!NOTATION png SYSTEM "http://some-other-kind-of-URL">
<!ELEMENT img EMPTY>
<!ATTLIST img
src ENTITY
alt CDATA #IMPLIED >
Then in my document i could write:
<!DOCTYPE img PUBLIC "-//Bizarro HTML" "http://bizarrohtml" [
<!ENTITY lena SYSTEM "lena.jpg" NDATA jpg>
]>
<img src="lena" alt="picture of Lena"/>
?
Can i also use that entity in regular text, like:
<p>Here is a picture of Lena &lena;</p>
?
And in both cases, what does it *mean*? If i parsed that into DOM and
called getAttribute("src") on the img element, what would i get back?
What's the point of being able to declare an attribute as being of type
NOTATION?
And does anyone actually use any of this stuff?
tom
I can see from the XML spec what processing instructions and notations
are, syntactically. I even just about understand how notations relate to
external entities. But i don't understand what you'd actually use them for
in practice!
The one example i've found is using an xml-stylesheet PI to specify a
stylesheet. Are there others?
How about notations and external entities? Is the idea that they're a
mechanism of linkage to external files that's more concrete than just
using a URL? So, if i was writing a bizarro world HTML, i could specify
images like this in the DTD:
<!NOTATION jpeg SYSTEM "http://some-kind-of-URL">
<!NOTATION png SYSTEM "http://some-other-kind-of-URL">
<!ELEMENT img EMPTY>
<!ATTLIST img
src ENTITY
alt CDATA #IMPLIED >
Then in my document i could write:
<!DOCTYPE img PUBLIC "-//Bizarro HTML" "http://bizarrohtml" [
<!ENTITY lena SYSTEM "lena.jpg" NDATA jpg>
]>
<img src="lena" alt="picture of Lena"/>
?
Can i also use that entity in regular text, like:
<p>Here is a picture of Lena &lena;</p>
?
And in both cases, what does it *mean*? If i parsed that into DOM and
called getAttribute("src") on the img element, what would i get back?
What's the point of being able to declare an attribute as being of type
NOTATION?
And does anyone actually use any of this stuff?
tom