universe and can be referenced as a group: a hypothetical RDF Graph Universal Quantifiers / Variables. (relevant references): OWL Definition of SWRL. (browse) SWRL/RuleML Variable Terms Terms are the kinds of objects that can appear in a quoted/asserted triple. This includes those that are core to RDF: Blank Nodes URI References Literals (which consist of a literal value, datatype and language tag) Those that extend the RDF model into N3: Formulae Universal Quantifications (Variables) And those that are primarily for matching against 'Nodes' in the underlying Graph: REGEX Expressions Date Ranges Numerical Ranges Nodes Nodes are a subset of the Terms that the underlying store actually persists. The set of such Terms depends on whether or not the store is formula-aware. Stores that aren't formula-aware would only persist those terms core to the RDF Model, and those that are formula-aware would be able to persist the N3 extensions as well. However, utility terms that only serve the purpose for matching nodes by term-patterns probably will only be terms and not nodes. "The set of nodes of an RDF graph is the set of subjects and objects of triples in the graph. Context-aware An RDF store capable of storing statements within contexts is considered context-aware. Essentially, such a store is able to partition the RDF model it represents into individual, named, and addressable sub-graphs. Formula-aware An RDF store capable of distinguishing between statements that are asserted and statements that are quoted is considered formula-aware. Such a store is responsible for maintaining this separation and ensuring that queries against the entire model (the aggregation of all the contexts - specified by not limiting a 'query' to a specifically name context) do not include quoted statements. Also, it is responsible for distinguishing universal quantifiers (variables). These 2 additional concepts (formulae and variables) must be thought of as core extensions and distinguishable from the other terms of a triple (for the sake of the persistence roundtrip - at the very least). It's worth noting that the 'scope' of universal quantifiers (variables) and existential quantifiers (BNodes) is the formula (or context - to be specific) in which their statements reside. Beyond this, a Formula-aware store behaves the same as a Context-aware store. Conjunctive Query Any query that doesn't limit the store to search within a named context only. Such a query expects a context-aware store to search the entire asserted universe (the conjunctive graph). A