I am always confused with multiple attribute clauses. For example:

... a complete virtual system composed of virtualized hardware components onto which an unmodified operating system can be installed.

For the "onto which an unmodified operating system call be installed." clause, does the which point to hardware components or a complete virtual system?  Does the attribute clause always modify the nearest noun?

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    'When tigers are living close to people, those known to be violent should be shot.' is a clear counterexample. The nearest NP that matches grammatically, logically etc ('There's a radio with two aerials that is made of aluminium' / 'I passed a man on a horse who/which looked very tired' / 'If the lava reaches the stone wall, it may change direction / collapse. ') has a strong claim to be considered the antecedent ... but ambiguities can certainly arise. Commented Mar 4 at 16:40

2 Answers 2


Your question doesn't seem to be so much about what a clause modifies, but about how to determine the antecedent of a relative pronoun, (the noun referred to by that pronoun), in this case, "which." There are several considerations in making that determination.

  • Proximity. The modifying clause has a strong attraction to the nearest preceding noun, which as you've spotted, makes "hardware components" a candidate.

  • Syntax. Sometimes you will have grammatical help that will tell you whether the nearest noun is the antecedent. Consider the following version of your example:

    Complete virtual systems composed of virtualized hardware which are available for the installation of an unmodified operating system.

    The plural verb "are" makes the only possible antecedent the plural noun "systems."

  • Punctuation. When a comma precedes a relative clause, that clause is non-restrictive, that is, informational only. If there's no comma, that clause is restrictive or defining, and restrictive clauses almost always modify the thing they immediately follow. (In AmE, restrictive clauses use the relative pronoun "that"; non-restrictive clauses, "which." This rule is unknown in BrE.) Let's look at two other versions:

    a complete virtual system composed of virtualized hardware, which is available for under $100. (non-restrictive, antecedent is ambiguous)

    a complete virtual system composed of virtualized hardware that is available for under $100. (restrictive, antecedent is "hardware")

  • Semantics. Sometimes you have to look at the sense of the sentence to determine the antecedent. In your case, it's very unlikely that an operating system will be installed on hardware components, virtualized or not. Operating systems are installed on computers or computer systems. The problem with relying on the semantics is that you interrupt the flow of reading as your audience searches for the other clues. Rephrase to be kind:

    We can install an unmodified operating system on a complete virtual system composed of virtualized hardware components.

Note that silly things can happen if you rely on meaning:

I had a hat on my head, which went astray.

What got lost has to be the hat, but the sentence still conjures up the image of a missing head.

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    Very detailed explanation! Thanks very much for your time and effort!
    – Nan Xiao
    Commented Jul 9, 2015 at 1:04
  • Sorry for stirring up old bones, but this question was recently tagged as a duplicate of a new one. Commented Sep 26, 2020 at 20:34
  • I don’t understand your assertion that a restrictive clause must refer to the closest possible antecedent.  Consider: “The food supply chain depends on trucks full of groceries that run day and night.”  The clause is restrictive — the schedule isn’t an incidental (informational) fact; the operation depends on it.  But clearly (by context / semantics) it is the trucks that run 24 hours a day.  See also Edwin Ashworth’s example, When tigers are living close to people, those known to be violent should be shot. Commented Sep 26, 2020 at 20:34

In the case of your sample fragment, I would say yes, it modifies the nearest noun phrase, virtualized hardware components.

To make it refer to the earlier noun phrase a complete virtual system, you would need to add commas (or better yet, parentheses), like so:

  • a complete virtual system, consisting of virtualized hardware components, onto which an unmodified operating system can be installed

  • a complete virtual system (consisting of virtualized hardware components) onto which an unmodified operating system can be installed

  • While I think your linguistic argument is sound, the resulting original sentence seems to make little sense if interpreted this way. The unmodified operating system will need to be installed onto the complete virtual system not on the individual virtualized hardware components.
    – DRF
    Commented Jul 8, 2015 at 6:25
  • I agree. That's why I showed how to fix it to say just that! Commented Jul 10, 2015 at 6:50

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