CLOSE OFF ROME AND BERLIN? (5,8)

I believe the answer is:

block capitals

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'close off rome and berlin?' is the definition.
I can't tell whether this definition defines the answer.

'close off rome and berlin?' is the wordplay.
'close off' becomes 'block' (block can mean to close or seal off).
'rome' becomes 's' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'and' says to put letters next to each other.
'berlin?' becomes 'capital' (berlin is a kind of capital).
's' put after 'capital' is 'capitals'.
'block'+'capitals'='BLOCK CAPITALS'

Can you help me to learn more?

(Another definition for block capitals that I've seen is " Upper case letters".)

I've seen this clue in The Independent.

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