Media Type and Content Encoding

The media type of TriG is application/trig. The content encoding of TriG content is always UTF-8.

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.

Comments

Comments in TriG take the form of '#', outside an IRI or a string, and continue to the end of line (marked by characters U+000D or U+000A) or end of file if there is no end of line after the comment marker. Comments are treated as white space.

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 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.

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 '\'.

%-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.

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]]. 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]].

Parser State

Parsing TriG requires a state of six items:

• IRI baseURI — When the base production is reached, the second rule argument, IRIREF, is the base URI used for relative IRI resolution.
• Map[prefix -> IRI] 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)? ":".
• Map[string -> blank node] bnodeLabels — A mapping from string to blank node.
• RDF_Term curSubject — The curSubject is bound to the subject production.
• RDF_Term 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.
• RDF_Term 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.

RDF Term Constructors

This table maps productions and lexical tokens to RDF terms or components of RDF terms listed in :

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.