Quand ouvre-t-on les cadeaux?

Question

What is the meaning of the ‘t’ in the phrase ‘ouvre-t-on’?

Accepted Answer

No meaning. It is there for pronunciation purposes only when forming inverted verbs ending in a vowel with il/elle/on.  
https://french.kwiziq.com/revision/grammar/forming-questions-by-inverting-in-the-present-tense-il-elle-on-forms

Answer

I think That it may have two meanings
Quand ouvre-t-on les cadeaux?(when do we open the gifts=because "on" can be used for "we")
Quand ouvre-t-on les cadeaux?( when are the gifts opened= because "on" can be used for anonymous subjects in passive sentences

Answer

Its just a liaison for pronunciation because there are two vowels together otherwise

Answer

When noun is ending with vowel and subject is starting with vowel we have to add -t- in between them.