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] format.
Status of This DocumentThis 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/.
This document is part of the RDF 1.1 document suite. 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]. 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 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.
Please see the Working Group's implementation report.
This document has been reviewed by W3C Members, by software developers, and by other W3C groups and interested parties, and is endorsed by the Director as a W3C Recommendation. It is a stable document and may be used as reference material or cited from another document. W3C's role in making the Recommendation is to draw attention to the specification and to promote its widespread deployment. This enhances the functionality and interoperability of the Web.
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.
Table of Contents 1. IntroductionThis document defines TriG, a concrete syntax for RDF as defined in the RDF Concepts and Abstract Syntax document [RDF11-CONCEPTS]. TriG is an extension of Turtle [TURTLE], extended to support representing a complete RDF Dataset.
2. TriG LanguageThis section is non-normative.
A TriG document allows writing down an RDF Dataset in a compact textual form. It consists of a sequence of directives, triple statements, graph statements which contain triple-generating statements and optional blank lines. Comments may be given after a # that is not part of another lexical token and continue to the end of the line.
Graph statements are a pair of an IRI or blank node label and a group of triple statements surrounded by {}. The IRI or blank node label of the graph statement may be used in another graph statement which implies taking the union of the tripes generated by each graph statement. An IRI or blank node label used as a graph label may also reoccur as part of any triple statement. Optionally a graph statement may not not be labeled with an IRI. Such a graph statement corresponds to the Default Graph of an RDF Dataset.
The construction of an RDF Dataset from a TriG document is defined in section 4. TriG Grammar and section 5. Parsing.
2.1 Triple StatementsAs TriG is an extention of the Turtle language it allows for any constructs from the Turtle language. Simple Triples, Predicate Lists, and Object Lists can all be used either inside a graph statement, or on their own as in a Turtle document. When outside a graph statement, the triples are considered to be part of the default graph of the RDF Dataset.
2.2 Graph StatementsA graph statement pairs an IRI or blank node with a RDF graph. The triple statements that make up the graph are enclosed in {}.
In a TriG document a graph IRI or blank node may be used as label for more than one graph statements. The graph label of a graph statement may be omitted. In this case the graph is considered the default graph of the RDF Dataset.
A RDF Dataset might contain only a single graph.
Example 1
# This document encodes one graph.
@prefix ex: <http://www.example.org/vocabulary#> .
@prefix : <http://www.example.org/exampleDocument#> .
:G1 { :Monica a ex:Person ;
ex:name "Monica Murphy" ;
ex:homepage <http://www.monicamurphy.org> ;
ex:email <mailto:monica@monicamurphy.org> ;
ex:hasSkill ex:Management ,
ex:Programming . }
A RDF Dataset may contain a default graph, and named graphs.
Example 2
# This document contains a default graph and two named graphs.
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix dc: <http://purl.org/dc/terms/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
# default graph
{
<http://example.org/bob> dc:publisher "Bob" .
<http://example.org/alice> dc:publisher "Alice" .
}
<http://example.org/bob>
{
_:a foaf:name "Bob" .
_:a foaf:mbox <mailto:bob@oldcorp.example.org> .
_:a foaf:knows _:b .
}
<http://example.org/alice>
{
_:b foaf:name "Alice" .
_:b foaf:mbox <mailto:alice@work.example.org> .
}
TriG provides various alternative ways to write graphs and triples, giving the data writer choices for clarity:
Example 3
# This document contains a same data as the
previous example.
@prefix rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#> .
@prefix dc: <http://purl.org/dc/terms/> .
@prefix foaf: <http://xmlns.com/foaf/0.1/> .
# default graph - no {} used.
<http://example.org/bob> dc:publisher "Bob" .
<http://example.org/alice> dc:publisher "Alice" .
# GRAPH keyword to highlight a named graph
# Abbreviation of triples using ;
GRAPH <http://example.org/bob>
{
[] foaf:name "Bob" ;
foaf:mbox <mailto:bob@oldcorp.example.org> ;
foaf:knows _:b .
}
GRAPH <http://example.org/alice>
{
_:b foaf:name "Alice" ;
foaf:mbox <mailto:alice@work.example.org>
}2.3 Other Terms
All other terms and directives come from Turtle.
2.3.1 Special Considerations for Blank NodesBlankNodes sharing the same label in differently labeled graph statements are considered to be the same BlankNode.
3. ConformanceAs well as sections marked as non-normative, all authoring guidelines, diagrams, examples, and notes in this specification are non-normative. Everything else in this specification is normative.
The key words MUST, MUST NOT, REQUIRED, SHOULD, SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this specification are to be interpreted as described in [RFC2119].
This specification defines conformance criteria for:
A conforming TriG document is a Unicode string that conforms to the grammar and additional constraints defined in section 4. TriG Grammar, starting with the trigDoc production. A TriG document serializes an RDF dataset.
A conforming TriG parser is a system capable of reading TriG documents on behalf of an application. It makes the serialized RDF dataset, as defined in section 5. Parsing, available to the application, usually through some form of API.
The IRI that identifies the TriG language is: http://www.w3.org/ns/formats/TriG
Note
This specification does not define how TriG parsers handle non-conforming input documents.
3.1 Media Type and Content EncodingThe media type of TriG is application/trig. The content encoding of TriG content is always UTF-8.
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 SpaceWhite 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 ReferencesRelative 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 TriG 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.
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+005Creserved 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.
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]. Production labels consisting of a number and a final 's', e.g. [60s], reference the production with that number in the document SPARQL 1.1 Query Language grammar [SPARQL11-QUERY].
Notes:
@base', '@prefix', 'a', 'true', 'false') are case-sensitive. Keywords in double quotes ( "BASE", "PREFIX" "GRAPH" ) are case-insensitive.\u, \U and those in ECHAR are case sensitive.trigDoc.ANON ::= '[' WS* ']' token allows any amount of white space and comments between []s. The single space version is used in the grammar for clarity.@prefix' and '@base' match the pattern for LANGTAG, though neither "prefix" nor "base" are registered language subtags. This specification does not define whether a quoted literal followed by either of these tokens (e.g. "Z"@base) is in the TriG language.The RDF Concepts and Abstract Syntax [RDF11-CONCEPTS] specification defines three types of RDF Term: IRIs, literals and blank nodes. Literals are composed of a lexical form and an optional language tag [BCP47] or datatype IRI. An extra type, prefix, is used during parsing to map string identifiers to namespace IRIs. This section maps a string conforming to the grammar in section 4.5 Grammar to a set of triples by mapping strings matching productions and lexical tokens to RDF terms or their components (e.g. language tags, lexical forms of literals). Grammar productions change the parser state and emit triples.
Parsing TriG requires a state of six items:
baseURI — When the base production is reached, the second rule argument, IRIREF, is the base URI used for relative IRI resolution.namespaces — The second and third rule arguments (PNAME_NS and IRIREF) in the prefixID production assign a namespace name (IRIREF) for the prefix (PNAME_NS). Outside of a prefixID production, any PNAME_NS is substituted with the namespace. Note that the prefix may be an empty string, per the PNAME_NS, production: (PN_PREFIX)? ":".bnodeLabels — A mapping from string to blank node.curSubject — The curSubject is bound to the subject production.curPredicate — The curPredicate is bound to the verb production. If token matched was "a", curPredicate is bound to the IRI http://www.w3.org/1999/02/22-rdf-syntax-ns#type.curGraph — The curGraph is bound to the label of the graph that is the destination of triples produced in parsing. When undefined, triples are destined for the default graph.This table maps productions and lexical tokens to RDF terms or components of RDF terms listed in section 5. Parsing:
prefix is the potentially empty unicode string matching the first argument of the rule is a key into the namespaces map. IRI When used in a PrefixedName production, the iri is the value in the namespaces map corresponding to the first argument of the rule. PNAME_LN IRI A potentially empty prefix is identified by the first sequence, PNAME_NS. The namespaces map MUST have a corresponding namespace. The unicode string of the IRI is formed by unescaping the reserved characters in the second argument, PN_LOCAL, and concatenating this onto the namespace. STRING_LITERAL_SINGLE_QUOTE lexical form The characters between the outermost "'"s are taken, with numeric and string escape sequences unescaped, to form the unicode string of a lexical form. STRING_LITERAL_QUOTE lexical form The characters between the outermost '"'s are taken, with numeric and string escape sequences unescaped, to form the unicode string of a lexical form. STRING_LITERAL_LONG_SINGLE_QUOTE lexical form The characters between the outermost "'''"s are taken, with numeric and string escape sequences unescaped, to form the unicode string of a lexical form. STRING_LITERAL_LONG_QUOTE lexical form The characters between the outermost '"""'s are taken, with numeric and string escape sequences unescaped, to form the unicode string of a lexical form. LANGTAG language tag The characters following the @ form the unicode string of the language tag. RDFLiteral literal The literal has a lexical form of the first rule argument, String, and either a language tag of LANGTAG or a datatype IRI of iri, depending on which rule matched the input. If the LANGTAG rule matched, the datatype is rdf:langString and the language tag is LANGTAG. If neither a language tag nor a datatype IRI is provided, the literal has a datatype of xsd:string. INTEGER literal The literal has a lexical form of the input string, and a datatype of xsd:integer. DECIMAL literal The literal has a lexical form of the input string, and a datatype of xsd:decimal. DOUBLE literal The literal has a lexical form of the input string, and a datatype of xsd:double. BooleanLiteral literal The literal has a lexical form of the true or false, depending on which matched the input, and a datatype of xsd:boolean. BLANK_NODE_LABEL blank node The string matching the second argument, PN_LOCAL, is a key in bnodeLabels. If there is no corresponding blank node in the map, one is allocated. ANON blank node A blank node is generated. blankNodePropertyList blank node A blank node is generated. Note the rules for blankNodePropertyList in the next section. collection blank node For non-empty lists, a blank node is generated. Note the rules for collection in the next section. IRI For empty lists, the resulting IRI is rdf:nil. Note the rules for collection in the next section. 5.3 RDF Triples Construction
A TriG document defines an RDF Dataset composed of one default graph and zero or more named graphs. Each graph is composed of a set of RDF triples.
5.3.1 Output GraphThe state curGraph is initially unset. It records the label of the graph for triples produced during parsing. If undefined, the default graph is used.
The rule labelOrSubject sets both curGraph and curSubject (only one of these will be used).
The following grammar production clauses set curGraph to be undefined, indicating the default graph:
The grammar production labelOrSubject predicateObjectList '.' unsets curGraph before handling predicateObjectLists in rule triplesOrGraph.
Each RDF triple produced is added to curGraph, or the default graph if curGraph is not set at that point in the parsing process.
The subject production sets the curSubject. The verb production sets the curPredicate.
Triples are produced at the following points in the parsing process and each RDF triple produced is added to the graph identified by curGraph.
Each object N in the document produces an RDF triple: curSubject curPredicate N.
Beginning the blankNodePropertyList production records the curSubject and curPredicate, and sets curSubject to a novel blank node B. Finishing the blankNodePropertyList production restores curSubject and curPredicate. The node produced by matching blankNodePropertyList is the blank node B.
Beginning the collection production records the curSubject and curPredicate. Each object in the collection production has a curSubject set to a novel blank node B and a curPredicate set to rdf:first. For each object objectn after the first produces a triple:objectn-1 rdf:rest objectn . Finishing the collection production creates an additional triple curSubject rdf:rest rdf:nil . and restores curSubject and curPredicate The node produced by matching collection is the first blank node B for non-empty lists and rdf:nil for empty lists.
This section is non-normative.
The editors gratefully acknowledge the work of Chris Bizer and Richard Cyganiak in creating the original TriG specification. Valuable contributions to this version were made by Gregg Kellogg, Eric Prud'hommeaux and Sandro Hawke.
The document was improved through the review process by the wider community.
A. Differences from Previous TriGThis section is non-normative.
This section describes the main differences between TriG, as defined in this document, and earlier forms.
{ ... }.= graph naming operator or optional "." after each graph.BASE, PREFIX as in [TURTLE].GRAPH keyword is allowed to aid SPARQL alignment.The Internet Media Type / MIME Type for TriG is "application/trig".
It is recommended that TriG files have the extension ".trig" (all lowercase) on all platforms.
It is recommended that TriG files stored on Macintosh HFS file systems be given a file type of "TEXT".
This information that follows will be submitted to the IESG for review, approval, and registration with IANA.
Error in grammar productions [24] and [25] fixed.
D. References D.1 Normative referencesRetroSearch is an open source project built by @garambo | Open a GitHub Issue
Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo
HTML:
3.2
| Encoding:
UTF-8
| Version:
0.7.3