Abstract
The Resource Description Framework
(RDF) is a
general-purpose language for representing information in the Web.
This document defines a textual syntax for RDF called TriG
that allows an RDF dataset to be completely written in a compact and
natural text form, with abbreviations for common usage patterns and
datatypes. TriG is an extension of the
Turtle [TURTLE-TR] format.
Status of This Document
This section describes the status of this document at the time of its publication. Other
documents may supersede this document. A list of current W3C publications and the latest revision
of this technical report can be found in the W3C technical reports
index at http://www.w3.org/TR/.
TriG is intended the meet the charter requirement of the
RDF Working Group to
define an RDF syntax for multiple graphs. TriG is an extension of the
Turtle syntax for RDF [[!TURTLE-TR]. The current document is based on
the original proposal by Chris Bizer and Richard Cyganiak.
This document was published by the RDF Working Group as a First Public Working Draft.
This document is intended to become a W3C Recommendation.
If you wish to make comments regarding this document, please send them to
public-rdf-comments@w3.org
(subscribe,
archives).
All comments are welcome.
Publication as a First Public Working Draft does not imply endorsement by the W3C Membership.
This is a draft document and may be updated, replaced or obsoleted by other documents at
any time. It is inappropriate to cite this document as other than work in progress.
This document was produced by a group operating under the
5 February 2004 W3C Patent Policy.
W3C maintains a public list of any patent disclosures
made in connection with the deliverables of the group; that page also includes instructions for
disclosing a patent. An individual who has actual knowledge of a patent which the individual believes contains
Essential Claim(s) must disclose the
information in accordance with section
6 of the W3C Patent Policy.
1. Introduction
This document defines TriG a concrete syntax for RDF as defined in the
RDF Concepts and Abstract Syntax
([RDF11-CONCEPTS]). TriG is an extension of
Turtle ([TURTLE-TR]), extended
to support representing a complete RDF Dataset.
4. TriG Grammar
A TriG document is a
Unicode[UNICODE]
character string encoded in UTF-8.
Unicode characters only in the range U+0000 to U+10FFFF inclusive are
allowed.
4.1 White Space
White space (production WS) is used to separate two terminals which would otherwise be (mis-)recognized as one terminal. Rule names below in capitals indicate where white space is significant; these form a possible choice of terminals for constructing a TriG parser.
White space is significant in the production String.
4.3 IRI References
Relative IRIs are resolved with base IRIs as per Uniform Resource Identifier (URI): Generic Syntax [RFC3986] using only the basic algorithm in section 5.2.
Neither Syntax-Based Normalization nor Scheme-Based Normalization (described in sections 6.2.2 and 6.2.3 of RFC3986) are performed.
Characters additionally allowed in IRI references are treated in the same way that unreserved characters are treated in URI references, per section 6.5 of Internationalized Resource Identifiers (IRIs) [RFC3987].
The @base directive defines the Base IRI used to resolve relative IRIs per RFC3986 section 5.1.1, "Base URI Embedded in Content".
Section 5.1.2, "Base URI from the Encapsulating Entity" defines how the In-Scope Base IRI may come from an encapsulating document, such as a SOAP envelope with an xml:base directive or a mime multipart document with a Content-Location header.
The "Retrieval URI" identified in 5.1.3, Base "URI from the Retrieval URI", is the URL from which a particular Turtle document was retrieved.
If none of the above specifies the Base URI, the default Base URI (section 5.1.4, "Default Base URI") is used.
Each @base directive sets a new In-Scope Base URI, relative to the previous one.
4.4 Escape Sequences
There are three forms of escapes used in TriG documents:
-
numeric escape sequences represent Unicode code points:
| Escape sequence |
Unicode code point |
| '\u' hex hex hex hex |
A Unicode character in the range U+0000 to U+FFFF inclusive
corresponding to the value encoded by the four hexadecimal digits interpreted from most significant to least significant digit. |
| '\U' hex hex hex hex hex hex hex hex |
A Unicode character in the range U+0000 to U+10FFFF inclusive
corresponding to the value encoded by the eight hexadecimal digits interpreted from most significant to least significant digit. |
where HEX is a hexadecimal character
HEX
::= [0-9] | [A-F] | [a-f]
-
string escape sequences represent the characters traditionally escaped in string literals:
| Escape sequence |
Unicode code point |
| '\t' |
U+0009 |
| '\b' |
U+0008 |
| '\n' |
U+000A |
| '\r' |
U+000D |
| '\f' |
U+000C |
| '\"' |
U+0022 |
| '\'' |
U+0027 |
| '\\' |
U+005C |
-
reserved character escape sequences consist of a '\' followed by one of ~.-!$&'()*+,;=/?#@%_ and represent the character to the right of the '\'.
Note
%-encoded sequences are in the character range for IRIs and are explicitly allowed in local names. These appear as a '%' followed by two hex characters and represent that same sequence of three characters. These sequences are not decoded during processing. A term written as <http://a.example/%66oo-bar> in TriG designates the IRI http://a.example/%66oo-bar and not IRI http://a.example/foo-bar. A term written as ex:%66oo-bar with a prefix @prefix ex: <http://a.example/> also designates the IRI http://a.example/%66oo-bar.
4.5 Grammar
The EBNF used here is defined in XML 1.0
[EBNF-NOTATION]. Production labels consisting of a number and a final 'g' are unique to TriG. All Production labels consisting of only a number reference the production with that number in the Turtle grammar [TURTLE-TR]. Production labels consisting of a number and a final 's', e.g. [60s], reference the production with that number in the SPARQL Query Language for RDF grammar [RDF-SPARQL-QUERY].
5. Parsing
Issue 4
Define a method of parsing that treats each graph statement as a Turtle document. Merge any graph statements that have the same label, or if they don't have a label merge to form the default graph.