In both speech and writing, there is a fairly straightforward formal distinction 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 an intonational 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 providing additional information; cf. Section 16.1.2. In written language, the intonation pattern is represented by the absence or presence of a comma: a non-restrictive modifier is preceded and followed by a comma, whereas these commas (especially the first one) are usually absent in the case of a restrictive modifier. This is illustrated in (3) for PP-modifiers: in (3a), the commas are missing and the PP-modifier in de schuurin the shed is interpreted as a restrictive modifier; in (3b) the PP in de Glazen Koetsin the Glass Coach functions as a non-restrictive modifier and is therefore preceded and followed by a comma (i.e. an intonation break).

In (4) we show the same thing for AP-modifiers such as verliefdin love: the adjective verliefdin love in (4a) forms an intonational unit with the proper noun and functions as a restrictive modifier, whereas the AP tot over zijn oren verliefdhead over heels in love in (4b) is separated from the noun by an intonation break 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, whereas restrictive relative clauses usually are not (although they may be followed by one).

In written language, the use of a comma after the restrictive relative clause is essentially optional, but common when the modified noun phrase is a subject. In particular, it is used when the verb of the relative clause immediately precedes the finite verb of the main clause, as in (6), or when the relative clause is long or complex. Note also that a restrictive clause can also be preceded by a comma if there is another (restrictive) postmodifier 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 can safely conclude that the relative clause is intended to be restrictive, but not all relative clauses preceded by a comma are intended to be non-restrictive. The conventions for 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 can be adjectival, participial, or infinitival in nature, is not separated from the head noun by a comma (unless it is clearly parenthetical). Thus, the adjective dapperebrave in example (8a) can be either restrictive (not all Germans, only the brave ones) or non-restrictive (the Germans, who are all brave). Similarly, there are no commas in either (8b) or (8b'), although they differ in the interpretation of the modifier: the adjective heerlijkdelicious in (8b) is likely to receive a non-restrictive interpretation (all the apples under discussion are delicious), whereas the adjective rodered in (8b') is likely to be given a restrictive interpretation (not the green ones).

In speech, on the other hand, the difference between restrictive and non-restrictive premodifiers is often indicated: restrictive premodifiers are usually stressed (especially 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.

Again, this difference does not apply to all cases. In (8b), for instance, the adjective can be stressed even when it is used non-restrictively, in which case the property heerlijkdelicious is emphatically stressed for its own sake, not to restrict the denotation of the noun phrase or to indicate contrast.