So far, to identify the sentence structure regarding RIF-FLD i made use of “analytical English,” a special type of English to own interacting analytical meanings, instances, an such like. The second products towards EBNF notation is going to be kept in mind:
LOCATOR
- The new sentence structure out-of RIF-FLD depends on the newest trademark device in fact it is perhaps not framework-free, very EBNF doesn’t need this syntax accurately. As a result, the brand new EBNF grammar describes a tight superset out of RIF-FLD (not absolutely all formulas that will be derivable by using the EBNF sentence structure is actually 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 Label Name . Identity, 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 represent a tangible sentence structure simply for selling and buying rules, and therefore sentence structure are XML-dependent, gotten because a refinement and serialization of the EBNF sentence structure thru the newest speech-syntax-to-XML mapping to possess RIF-FLD.
Keeping the above planned, the brand new EBNF grammar can be seen once the merely an intermediary between the latest analytical English while the XML. However, it brings a brief look at new syntax of RIF-FLD and thus can be useful getting dialect music artists and you may users equivalent.
For each and every RIF-FLD formula and name is prefixed with that 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 tagged yükle [RIF-DTB]. 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
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 Frame 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].