The following two sentences are patentese (written in language used in a patent):
A display apparatus includes a display device for displaying an image.
The display apparatus may include an optical film for limiting reflection of external, ambient light.
In 'normal' general English, I would say that writing "to display" and "to limit" sounds more natural, where the "to" is short for "in order to", thus using the << noun + "to (in order to)" + infinitive >> noun phrase construction instead. Also, acceptable would be << noun + "for the purpose of" + gerund >>, but this is perhaps unnecessarily long-winded.
Doing a search online gives acceptable examples of the noun phrase construction << noun + "for" + gerund >> used in titles, for example:
A simple method for displaying the hydropathic character of a protein
Options for Limiting the Potential to Emit (PTE) of a Stationary Source Under Section 112 and Title V of the Clean Air Act (CAA)
For these titles (that are a noun phrase standalone construction without a verb), the << noun + "for" + gerund >> construction is valid and sounds natural to me, but what about if we change these into a normal sentence including verbs, for example:
We describe a simple method for displaying the hydropathic character of a protein.
There are options for limiting the potential to emit (PTE) of a stationary source under Section 112 and Title V of the Clean Air Act (CAA).
The latter quoted sentence sounds fine, but the former sounds a bit unnatural to me due to the << noun + "for" + gerund >> construction within.
[[My original question, referred to these two quotes of titles with this unintentionally misleading comment: But these seem to be missing a verb, if what is intended is a normal complete sentence.]]
So, I'd like to ask: Are the first two sentences quoted above acceptable? Do they sound natural? If not, why not and what are the best alternatives?