We’ll now specify the newest syntax making use of the familiar EBNF notation

Until now, to indicate the fresh new syntax of RIF-FLD we relied on “statistical English,” a special version of English for communicating statistical significance, advice, etc. Another activities regarding EBNF notation is stored in mind:

LOCATOR

• The fresh new sentence structure out-of RIF-FLD depends on brand new trademark mechanism and that is perhaps not context-100 % free, thus EBNF will not just take it syntax correctly. This means that, the fresh new EBNF sentence structure represent a rigid superset out-of RIF-FLD (never assume all formulas that are derivable utilising the EBNF grammar are well-formed).
• The EBNF syntax is not a concrete syntax: it does not address the details of how constants (defined in [RIF-DTB]) and variables are represented, and it is not sufficiently precise about the delimiters and escape symbols. White space is informally used as a delimiter, and is implied in productions that use Kleene star. For instance, TERM* is to be understood as Title Identity . Name, where each ‘ ‘ abstracts from one or more blanks, tabs, newlines, etc. This is done intentionally since RIF’s presentation syntax is used as a tool for specifying the semantics and for illustration of the main RIF concepts through examples.
• RIF defines a tangible syntax just for exchanging regulations, and therefore sentence structure is actually XML-created, obtained as an elegance and you can serialization of the EBNF syntax through the fresh new speech-syntax-to-XML mapping for RIF-FLD.

Staying these at heart, brand new EBNF grammar is visible as merely a mediator ranging from the fresh new analytical English plus the XML. However, additionally gives a succinct view of the fresh sentence structure out of RIF-FLD and as such can be handy getting dialect musicians and you can pages the exact same.

For each RIF-FLD algorithm and you can term should be prefixed which have one elective annotation

The RIF-FLD presentation syntax does not commit to any particular vocabulary and permits arbitrary sequences of Unicode characters in constant symbols, argument names, and variables. Such sequences are denoted with UNICODESTRING in the above syntax. Constant symbols have this form: "UNICODESTRING"^^SYMSPACE, where SYMSPACE is a ANGLEBRACKIRI or CURIE that represents the identifier of the symbol space of the constant. UNICODESTRING, ANGLEBRACKIRI, and CURIE are defined in Section Shortcuts for Constants in RIF’s Presentation Syntax of [RIF-DTB]. Constant symbols can also have several shortcut forms, which are represented by the non-terminal CONSTSHORT. These shortcuts are also defined in the same section of [RIF-DTB] http://datingranking.net/tr/wapa-inceleme/. One of them is the CURIE shortcut, which is used in the examples in this document. Names are Unicode character sequences that form valid XML NCNames [XML-Names]. Variables are composed of Names prefixed with a ?-sign.

, which is used in several places in the grammar, is a non-terminal whose definition is left to the dialects. It is intended to specify the protocol by which external sources, remote modules, and imported RIF documents are located. This must include the basic form , where IRI is a Unicode string in the form of an absolute IRI.

The symbols NEWCONNECTIVE, NEWQUANTIFIER, NEWAGGRFUNC, and NEWTERM are RIF-FLD extension points. They are not actual symbols in the alphabet. Instead, dialects are supposed to replace NEWCONNECTIVE, NEWQUANTIFIER, and NEWAGGRFUNC, by zero or more actual new symbols, while NEWTERM is to be replaced by zero or more new kinds of terms. Note that the extension point NEWSYMBOL is not shown in the EBNF grammar completely avoids mentioning the alphabet of the language (which is infinite).

IRIMETA, for identification and metadata. IRIMETA is represented using (*. *)-brackets that contain an optional rif:iri constant as identifier followed by an optional Figure or cones as metadata. One such specialization is '"' IRI '"^^' 'rif:iri' from the Const production, where IRI is a sequence of Unicode characters that forms an internationalized resource identifier as defined by [RFC-3987].