This section discusses the question as to whether postpositional phrases may undergo R-pronominalization, and it will show that it is not easy to answer this question. In view of the fact, illustrated in (65b), that nominal complements of postpositions can be pronominalized by means of a -R pronoun, one might expect R-pronominalization to be blocked. However, constructions such as (65b) often occur alongside constructions such as (65c), which involve R-pronominalization.

Of course, this may be accidental given that waar ... in in (65c) may be the pronominalized counterpart of the prepositional phrase in de boom in the change of location construction dat hij in die boom is geklommen, but speakers' intuitions concerning the semantic difference between the two examples in (65b&c) are generally not sharp enough to be conclusive.
      One test that may help to determine whether the pronominal PP in examples such as (65c) can be postpositional in nature or not is based on the observation that, like verbal particles, postpositions can permeate clause-final verb clusters, whereas (stranded) prepositions are not able to do this. This is illustrated in (66).

However, using permeation of the clause-final verb cluster as a test is problematic for various reasons. First, permeation of the verb cluster by a stranded preposition is perfectly acceptable in certain southern varieties of Dutch: see Section V4.3 and V4.5. The test will therefore only provide reliable results if we restrict ourselves to speakers of the northern part of the Netherlands.
      A second problem is that even those speakers who give the judgments in (66a') are often not very sure about their judgments on the relevant relative constructions, which may furthermore vary from case to case. Consider the examples in (67). Most northern speakers we consulted strongly prefer the use of a regular relative pronoun in (67a&b); the use of the relative R-pronoun waar in the corresponding primed examples is generally considered marked. The two alternatives in (67c&c'), on the other hand, are generally judged equally well and some speakers even prefer the use of the relative R-pronoun waar .

If the proposed test is reliable, we should conclude that the adpositions in and op in (67) are postpositional; they all permeate the verb cluster consisting of the auxiliary is and the past participle. This shows that we cannot account for the acceptability judgments in the (a)- and (b)-examples by assuming that some lexical restriction on the postposition itself is involved; R-pronominalization gives rise to a severely degraded result with the postposition in in (67a'), but to a fully grammatical result with the same postposition in (67c').
      A third problem is that there is evidence that goes against the claim that we are dealing with pronominalized postpositional phrases in the primed examples in (67). The examples in (68) show that the judgments on the use of the relative R-pronoun waar in the primed examples in (67) are more or less identical to those on the use of prepositional phrases in the primed examples in (68). This strongly suggests that the primed examples in (67) involve pronominalized prepositional phrases after all, which would imply in turn that postpositional phrases cannot undergo R-pronominalization.

This conclusion is also supported by the minimal pairs in (69) with the complex postposition achterna'after' and circumposition achter ... aan'after'. The primed examples show that the nominal complement of the postposition achterna can only be pronominalized by a -R pronoun, whereas it must be pronominalized by means of a [+R] pronoun in the case of the circumposition achter ... aan.

      The discussion above seems to show that the permeation test is not fully reliable and that, despite the fact that the stranded adpositions permeate the clause-final verb cluster, we are dealing with pronominalized prepositional phrases in the primed examples of (67). There is, however, also a problem with the claim that postpositional phrases do not allow R-pronominalization. Consider the resultative construction in (70), in which the postpositional phrase de haven in cannot be replaced by the prepositional phrase in de haven. Although pronominalization of the nominal complement of the postposition does not seem readily possible, the judgments on the relative construction in (70b) show that the relative pronoun must be an R-word: whereas the use of waar gives rise to a marked but reasonably acceptable result, the use of the regular pronoun die is (surprisingly) rejected by most speakers.

A second potential problem is constituted by example (71b). Since the adposition af cannot be used as a preposition, this example may involve a pronominalized postpositional phrase. In this case, however, there is also an alternative analysis, according to which the R-word does not act as a pronoun corresponding to the noun phrase de berg in (71a) but as a pro-form of the adpositional phrase van de berg.

      It will be clear from the discussion above that we are not yet able to provide an unambiguous answer to the question as to whether postpositional phrases can undergo R-pronominalization or not. If there really is a general ban on stranded prepositions within the verb cluster, we should conclude that R-pronominalization of postpositional phrases is possible (which will leaves us without an account for the relative grammaticality judgments in (67)). If it turns out that stranded prepositions can sometimes permeate the verb cluster, the answer depends on whether one is willing to declare (70b) grammatical with the R-word waar. If so, we may have to conclude that R-pronominalization of postpositional phrases is possible; if not, we can maintain that R-pronominalization of postpositional phrases is impossible (and thus account for the grammaticality judgments on the examples in (67) by referring to the similar judgments on the examples in (68)). Since we are not able to shed more light on this issue at this point, we have to leave this topic to future research, and simply conclude, despite the problematic cases discussed above, that postpositional phrases normally do not allow R-pronominalization.