N-Triples is a line-based, plain text format for encoding an RDF graph.
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/.N-Triples was originally defined as a syntax for the RDF Test Cases [RDF-TESTCASES] document. Due to its popularity as an exchange format the RDF Working Group decided to publish an updated version. In a change from previous publication, this document is intended to become a W3C Recommendation.
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This document defines an easy to parse line-based subset of Turtle [TURTLE] named N-Triples.
The syntax is a revised version of N-Triples as originally defined in the RDF Test Cases [RDF-TESTCASES] document. Its original intent was for writing test cases, but it has proven to be popular as an exchange format for RDF data.
An N-Triples document contains no parsing directives.
N-Triples triples are a sequence of RDF terms representing the subject, predicate and object of an RDF Triple. These may be separated by white space (spaces
U+0020 or tabs
U+0009). This sequence is terminated by a '
.' and a new line (optional at the end of a document).
N-Triples triples are also Turtle simple triples, but Turtle includes other representations of RDF terms and abbreviations of RDF Triples. When parsed by a Turtle parser, data in the N-Triples format will produce exactly the same triples as a parser for the N-triples language.
The RDF graph represented by an N-Triples document contains
exactly each triple matching the N-Triples
The simplest triple statement is a sequence of (subject, predicate, object) terms, separated by whitespace and terminated by '
.' after each triple.
IRIs may be written only as absolute IRIs.
IRIs are enclosed in '
<' and '
>' and may contain numeric escape sequences (described below). For example
Literals are used to identify values such as strings, numbers, dates.
Literals (Grammar production Literal) have a lexical form followed by a language tag, a datatype IRI, or neither.
The representation of the lexical form consists of an
" (U+0022), a sequence of permitted
characters or numeric escape sequence or string escape sequence, and a final delimiter. Literals may not contain the characters
CR except in their escaped forms. In addition '
\' (U+005C) may not appear in any quoted literal except as part of an escape sequence.
The corresponding RDF lexical form is the characters between the delimiters, after processing any escape sequences.
If present, the language tag is preceded by a '
If there is no language tag, there may be a datatype IRI, preceded by '
^^' (U+005E U+005E). If there is no datatype IRI and no language tag it is a simple literal and the datatype is
RDF blank nodes in N-Triples are expressed as
_: followed by a blank node label which is a series of name characters.
The characters in the label are built upon PN_CHARS_BASE, liberalized as follows:
[0-9]may appear anywhere in a blank node label.
.may appear anywhere except the first or last character.
U+2040are permitted anywhere except the first character.
A fresh RDF blank node is allocated for each unique blank node label in a document. Repeated use of the same blank node label identifies the same RDF blank node.
This section is non-normative.
\ffor backspace and form feed
As 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 N-Triple document is a Unicode string that conforms to the grammar and additional constraints defined in section 5. Grammar, starting with the
ntriplesDoc production. A N-Triple document serializes an RDF graph.
A canonical N-Triple document is a N-Triple document with additional constraints:
objectMUST be a single space, (
U+0020) all other locations that allow whitespace MUST be empty.
HEXMUST use only uppercase letters (
U+000D) MUST use
A conforming N-Triple parser is a system capable of reading N-Triple documents on behalf of an application. It makes the serialized RDF graph, as defined in section 6. Parsing, available to the application, usually through some form of API.
The IRI that identifies the N-Triple language is:
The media type of N-Triples is
The content encoding of N-Triples is always UTF-8.
See N-Triples Media Type for the media type
N-Triples has been historically provided with other media types. N-Triples may also be provided as
text/plain. When used in this way N-Triples MUST use the escaped form of any character outside US-ASCII. As N-Triples is a subset of Turtle a N-Triples document MAY also be provided as
text/turtle. In both of these cases the document is not an N-Triples document as an N-Triples document is only provided as
A N-Triples document is a Unicode [UNICODE] character string encoded in UTF-8. Unicode code points only in the range U+0 to U+10FFFF inclusive are allowed.
White space (tab
U+0009 or space
U+0020) is used to separate two terminals which would otherwise be (mis-)recognized as one terminal. White space is significant in the production STRING_LITERAL_QUOTE.
Comments in N-Triples take the form of '
#', outside an
STRING_LITERAL_QUOTE, and continue to the end of line (
EOL) or end of file if there is no end of line after the comment marker. Comments are treated as white space.
The EBNF used here is defined in XML 1.0 [EBNF-NOTATION].
Escape sequence rules are the same as Turtle
[TURTLE]. However, as only the
STRING_LITERAL_QUOTE production is allowed new lines in literals MUST be escaped.
||::=||triple? (EOL triple)
||::=||subject predicate object '
Productions for terminals
Parsing N-Triples requires a state of one item:
bnodeLabels— A mapping from string to blank node.
This table maps productions and lexical tokens to
RDF terms or components of
RDF terms listed in section 6. Parsing:
|IRIREF||IRI||The characters between "<" and ">" are taken, with escape sequences unescaped, to form the unicode string of the IRI.|
|STRING_LITERAL_QUOTE||lexical form||The characters between the outermost '"'s are taken, with escape sequences unescaped, to form the unicode string of a lexical form.|
|LANGTAG||language tag||The characters following the |
|literal||literal||The literal has a lexical form of the first rule argument, |
|BLANK_NODE_LABEL||blank node||The string after '|
A N-Triple document defines an RDF graphs composed of a set of RDF triples. The
triple production produces a triple defined by the terms constructed for
This section is non-normative.
The editor of the 2013 edition acknowledges valuable contributions from Gregg Kellogg, Andy Seaborn, Eric Prud'hommeaux, Dave Beckett, David Robillard, Gregory Williams, Pat Hayes, Richard Cyganiak, Henry S. Thompson, and David Booth.
This specification is a product of extended deliberations by the members of the RDF Working Group. It draws upon the earlier specification in RDF Test Cases, edited by Dave Beckett.
No substitutive changes.
The Internet Media Type / MIME Type for N-Triples is "application/n-triples".
It is recommended that N-Triples files have the extension ".nt" (all lowercase) on all platforms.
It is recommended that N-Triples 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.