Refugee Travel Document (No Citizenship on RTD)

[newstartC]

Here is the question, I traveled to the UK with my RTD,
and there is no citizenship marked on the RTD,
the border control asked for my citizenship, as it is not marked on the RTD.
And I can't proof my originally citizenship, and they let me in the UK with RTD.
But I wonder where and how do people proof their citizenship with an RTD?

 

[Flowercita]

Here is the question, I traveled to the UK with my RTD,
and there is no citizenship marked on the RTD,
the border control asked for my citizenship, as it is not marked on the RTD.
And I can't proof my originally citizenship, and they let me in the UK with RTD.
But I wonder where and how do people proof their citizenship with an RTD?

In your RTD states what is your country of origin. And is the only country where you cannot travel with it. Appears in second or third page.