Use of「ことがわかる」in this sentence


I encountered this sentence in an article from _NHK News web easy_ :

今まで国からお金をもらうためには、旅行した人が本当に利用したことがわかる書類などを「Go Toトラベル」の事務所に出さなければなりませんでした。

I cannot understand what 「 **本当に利用したことがわかる書類** 」means in this case. Ignoring
that part the remaining part of the sentence can be translated as: "Up until
now in order to get money from the government, people who have travelled, have
to send [ **missing part here** ] to the 「Go Toトラベル」office".

Now, I know that 利用する means "To use", and by inferring things, maybe, that
part can be roughly translated as " **the documents that do really certify
that they were on a trip** ", but I'm not sure and I cannot see how「
**本当に利用したことがわかる書類** 」carries that meaning.




You might be thinking of this meaning of わかる, which is the first meaning
you'll find in a monolingual dictionary.

> 物事の意味・価値などが理解できる  
>  To be able to understand the meaning, value, etc. of something

But the second definition is the one being used here.

> はっきりしなかった物事が明らかになる  
>  Something that was unclear becomes clear

So, 本当に利用したことがわかる書類 is "a document which makes it clear that [the traveler]
really used [whatever it is they used]"

If you check the "regular" NHK News version of the article, it appears this
phrase was NHK News Easy's way of explaining the word 宿泊証明書.




You might be thinking of this meaning of わかる, which is the first meaning
you'll find in a monolingual dictionary.

> 物事の意味・価値などが理解できる  
>  To be able to understand the meaning, value, etc. of something

But the second definition is the one being used here.

> はっきりしなかった物事が明らかになる  
>  Something that was unclear becomes clear

So, 本当に利用したことがわかる書類 is "a document which makes it clear that [the traveler]
really used [whatever it is they used]"

If you check the "regular" NHK News version of the article, it appears this
phrase was NHK News Easy's way of explaining the word 宿泊証明書.

