Both in speech and in written language, there is a fairly straightforward formal difference between restrictive and non-restrictive modifiers in postnominal position. In speech, restrictive and non-restrictive postnominal modifiers are formally distinguished by their intonation patterns: whereas in restrictive constructions the head and modifier form one intonation unit, non-restrictive constructions are characterized by an intonation break between the nominal head and the modifier. This use of an intonation break to separate off non-restrictive modifiers reflects the status of this modifier as supplying extra information; cf. Section 3.1.2. In written language, the intonation pattern is represented by, respectively, the lack or the presence of a comma: a non-restrictive modifier is preceded and followed by a comma, whereas these commas (in particular the first one) are normally absent in the case of a restrictive modifier. This is illustrated in (3) for PP-modifiers: in (3a), the commas are absent and the PP-modifier in de schuur'in the shed' is interpreted as a restrictive modifier; in (3b) the PP in de Gouden Koets'in the Golden Coach' functions as a non-restrictive modifier and is hence preceded and followed by an intonation break/a comma.

In (4), we show the same thing for AP-modifiers like verliefd'in love': the adjective verliefd'in love' in (4a) forms an intonation unit with the proper noun and functions as a restrictive modifier, whereas the AP tot over zijn oren verliefd'head over heels in love' in (4b) is separated from the noun by an intonation break/a comma and functions as a non-restrictive modifier.

With relative clauses we find essentially the same thing, although there are some complicating factors. The examples in (5) and (6) show that non-restrictive relative clauses are preceded and followed by an intonation break/a comma, whereas restrictive relative clauses are normally not (although they may be followed by one).

      In written language, the use of a comma following the restrictive relative clause is essentially optional but common if the modified noun phrase is a subject. In particular, it is used if the verb of the relative clause immediately precedes the finite verb of the main clause, as in (6), or if the relative clause is long or complex. Note further that a restrictive clause can also be preceded by a comma if there is another (restrictive) postmodifier in between the noun and the relative clause, as in (7). Obviously, this means that the status of the relative clause, as restrictive or non-restrictive, cannot always be inferred from the use of commas alone: if the commas are absent, we may safely conclude that the relative clause is intended as restrictive, but not all relative clauses preceded by a comma are intended as non-restrictive. The conventions on comma placement can be found in language guides such as Renkema (1989: 170ff.) and Van Gessel (1992: 108ff.).

In the case of premodification, there are no typographical differences between restrictive and non-restrictive constructions: the premodifier, which may be adjectival, participial or infinitival in nature, is not separated off from the head noun by means of a comma (unless it is clearly parenthetical). Thus the adjective dappere'brave' in example (8a) can be either restrictive (not all Germans but only the brave ones) or non-restrictive (the Germans, all of whom are brave). Similarly, there are no commas in either (8b) or (8b'), despite the fact that they differ in interpretation of the modifier: the adjective heerlijk'delicious' in (8b) is likely to receive a non-restrictive interpretation (all apples under discussion are delicious), whereas the adjective rode'red' in (8b') is likely to be given a restrictive interpretation (not the green ones).

In speaking, on the other hand, the difference between restrictive and non-restrictive premodifiers often is indicated: restrictive premodifiers are usually stressed (in particular in contrastive contexts), whereas non-restrictive premodifiers are not. This difference in emphasis would, for instance, distinguish the restrictive reading of (8a) from the non-restrictive one.

Once again, however, this difference does not apply to all cases. In (8b), for instance, the adjective may be stressed, even if it is used non-restrictively, in which case the property heerlijk'delicious' is emphatically stressed for its own sake, not to restrict the denotation of the noun phrase or to indicate contrast.