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RSS
Elements for 1.0 Tutorial - Protocol
<!--
A DTD for Dan's Kinda Hacky XML Validation
Format (DKHXVF)
Basically, this format allows us to
enforce some additional rules
that DTD's do not. Specifically, we
can:
- specify min and max for number of
each child element
- specify a regular expression that
text elements and attributes must match
- specify type of text elements and
attributes (int, float, string, timestamp)
- specify min and max for any type.
(length compare for strings, numeric
otherwise)
The hope is that this will allow the
rapid creation of new formats, and modification
of existing formats (adding/removing
tags, attributes etc), without requiring
code changes in the validation software.
This is not in any way intended to be
an alternative to XML schemas. In the
absence of code supporting XML schemas,
I created this, but it is meant as
a transitional work only.
For more on XML schemas, see:
http://www.w3.org/1999/05/06-xmlschema-1/
and
http://www.w3.org/1999/05/06-xmlschema-2/
This is also not meant to replace DTDs.
There are many things that you can do
with DTDs that you cannot do with this
format. For example, you cannot declare
entities with this format. You must
do that in the DTD. If you want your
parser to interpret them correctly,
you must use a validating parser.
It is possible to use these schemas
without DTD validation, however you
may run
into problems with entity expansion
and other things.
Dan Libby - danda@netscape.com
$Log: schema-1.0.dtd,v $
Revision 1.1.2.2 2001/11/09 08:10:07
dprusak
Merged for 6.2 Revision
1.1.2.1 2001/10/17 22:25:29 dprusak
NewMyNetscape
Revision 1.1.2.1 2001/05/03 00:44:50
hoangtv
adding DTD definition
Revision 1.1 1999/07/25 07:59:32 danda
DTDs for RSS
Revision 1.2 1999/07/22 07:17:03 danda
fixing spacing
Revision 1.1 1999/06/09 07:01:29 danda
adding schema and dtd for rss 0.9
and 1.0
-->
<!--
Tag: Schema
Description: Document wrapper.
Sub tags: Element & Attribute
Attributes: version, root, name
Notes:
version must be "DKHXVF 1.0"
root is the document root.
-->
<!ELEMENT Schema (Element | Attribute)*>
<!ATTLIST Schema
version CDATA #FIXED "DKHXVF
1.0"
root CDATA #REQUIRED
name CDATA #REQUIRED>
<!--
Tag: Element
Description: Definition of an allowed
element (tag)
Sub tags: Contains, Attrib, Matches
Attributes: id, type, min, max, exactly
Notes: exactly="1" is equivalent
to min="1" max="1"
-->
<!ELEMENT Element ((Contains |
Attrib)* | Matches?)>
<!ATTLIST Element
id CDATA #REQUIRED
type (int | float | container | string
| timestamp) #REQUIRED
min CDATA #IMPLIED
max CDATA #IMPLIED
exactly CDATA #IMPLIED>
<!--
Tag: Contains
Description: Defines rules for a sub-element.
Sub tags: None, this tag must be empty.
Attributes: ref, min, max, exactly
Notes: ref must refer to the 'id'
of an element defined elsewhere or
the schema
is invalid.
-->
<!ELEMENT Contains EMPTY>
<!ATTLIST Contains
ref CDATA #REQUIRED
min CDATA #IMPLIED
max CDATA #IMPLIED
exactly CDATA #IMPLIED>
<!--
Tag: Attrib
Description: Defines rules for an
element attribute.
Sub tags: None, this tag must be empty
Attributes: ref, min, max, exactly
Notes: ref must refer to the 'id'
of an Attribute defined elsewhere
or the schema
is invalid.
-->
<!ELEMENT Attrib EMPTY>
<!ATTLIST Attrib
ref CDATA #REQUIRED
min CDATA #IMPLIED
max CDATA #IMPLIED
exactly CDATA #IMPLIED>
<!--
Tag: Attribute
Description: Definition of an allowed
attribute
Sub tags: Matches
Attributes: id, type, min, max, exactly
Notes: none
-->
<!ELEMENT Attribute (Matches?)>
<!ATTLIST Attribute
id CDATA #REQUIRED
type (int | float | string | timestamp)
#REQUIRED
min CDATA #IMPLIED
max CDATA #IMPLIED
exactly CDATA #IMPLIED>
<!--
Tag: Matches
Description: A regular expression
that values will be compared against
Sub tags: None
Attributes: None
Notes: Matches may be used for elements
of any type but container, and for
attributes.
An example of a useful matching pattern
is:
<Matches>^(foo|bar|foobar)$</Matches>
This will allow any values that exactly
match "foo", "bar",
or "foobar".
Whitespace is allowed in the regex
and '#' is used for comments. The
following
is valid:
<Matches>
&# # Start of a numeric entity
reference, xml escaped &
(?P<char> # xml escaped
<, >
[0-9]+[^0-9] # Decimal form
| 0[0-7]+[^0-7] # Octal form
| x[0-9a-fA-F]+[^0-9a-fA-F] # Hexadecimal
form
)
</Matches>
which is equivalent to:
<Matches>&#(?P<char>[0-9]+[^0-9]|
0[0-7]+[^0-7]| x[0-9a-fA-F]+[^0-9a-fA-F])</Matches>
For help on regular expressions, see:
http://www.python.org/doc/howto/regex/regex.html
or
http://www.ciser.cornell.edu/info/regex.html
-->
<!ELEMENT Matches (#PCDATA)>
<!--
Example of a DKHXVF 1.0 file:
<?xml version="1.0"?>
<!DOCTYPE Schema PUBLIC "-//Netscape
Communications//DTD Schema 1.0//EN"
"http://my.netscape.com/publish/formats/schema-1.0.dtd">
<Schema version="DKHXVF 1.0"
root="rdf:RDF" name="RSS
0.9">
<Element id="rdf:RDF"
type="container">
<Contains ref="channel"
exactly="1"/>
<Contains ref="image"
min="0" max="1"/>
<Contains ref="item"
min="1" max="15"/>
<Contains ref="textinput"
min="0" max="1"/>
<Attrib ref="xmlns" exactly="1"/>
<Attrib ref="xmlns:rdf"
exactly="1"/>
</Element>
<Attribute id="xmlns"
type="string">
<Matches>http://my.netscape.com/rdf/simple/0.9/</Matches>
</Attribute>
<Attribute id="xmlns:rdf"
type="string">
<Matches>http://www.w3.org/1999/02/22-rdf-syntax-ns#</Matches>
</Attribute>
<Element id="channel"
type="container">
<Contains ref="link"
exactly="1"/>
<Contains ref="title"
exactly="1"/>
<Contains ref="description"
exactly="1"/>
</Element>
<Element id="item" type="container">
<Contains ref="title"
exactly="1"/>
<Contains ref="link"
exactly="1"/>
</Element>
<Element id="image" type="container">
<Contains ref="title"
exactly="1"/>
<Contains ref="link"
exactly="1" />
<Contains ref="url" exactly="1"/>
</Element>
<Element id="textinput"
type="container">
<Contains ref="title"
exactly="1"/>
<Contains ref="description"
exactly="1"/>
<Contains ref="link"
exactly="1"/>
<Contains ref="name"
exactly="1"/>
</Element>
<Element id="title" type="string"
min="1" max="100"/>
<Element id="description"
type="string" min="1"
max="500"/>
<Element id="url" type="string"
min="1" max="500">
<Matches>^(http://|^ftp://)</Matches>
</Element>
<Element id="link" type="string"
min="1" max="500">
<Matches>^(http://|^ftp://)</Matches>
</Element>
<Element id="name" type="string"
min="1" max="20"/>
</Schema>
-->
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