contract is the name of the relation,Order is the source concept of the relation,ContractID is the target concept of this relation, andUNI and TOT are constraints of this relation.RELATION owner[Person*Building], owner is the name and [Person*Building] is the type of the relation. Relation names start with a lower case character, to avoid confusion with concept names. The signature of this relation is owner[Person*Building]. The signature identifies the relation within its context. The left hand concept, Person, is called the source of the relation and the right concept, Building, is called the target.<properties> and <pragma>-parts are discussed in the sequel. The <meaning>-part is discussed here.name[Book*Name] can be specified in the same context as name[Person*Name]. Because they have different source concepts, these are different relations.<properties>-part is meant for writing multiplicity constraints in a comma separated list between square brackets '[' and ']'. E.g. [UNI,TOT] . The following properties can be specified on any relation r[A*B]a in A there can be not more than one b in B in the population of r. This implies that every a occurs not more than once (is unique) in the source of r.b in B there can be not more than one a in A in the population of r. So, every b occurs not more than once in the target of r.b in B there must be at least one a in A in the population of r.a in A there must be at least one b in B in the population of r.r[A*A].a,b) in r, (b,a) is in r.a,b) and (b,a) are both in r, then a = ba,b) and (b,c) are both in r, then (a,c) is in r.a in A, the pair (a,a) is in the population of ra in A, the pair (a,a) is not in the population of rPRAGMA. The PRAGMA is followed by two or three strings. It is used to construct sentences in natural language, using pairs from the actual population of a relation. A pragma specifies how we speak (in natural language) about any pair in the relation. Ampersand also uses pragmas to generate examples in the functional specification. Example of a pragma with three strings:(John,Amsterdam) results in the sentence "Student John flies the flag of Amsterdam in top.". The two atoms are fitted in between the three strings. A pragma with two strings is identical to a pragma in which the third string is empty.PRAGMA keyword will become obsolete in a future version of Ampersand. It will be replaced by the VIEW-statement which offers more flexibility in composing sentences.)PRAGMA tells us that it makes sense to utter the phrase "Provider Mario's Pizza's has accepted order 12345."