Eccentric coerced us to install old form of program (6,4)

I believe the answer is:

source code

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'form of program' is the definition.
The definition and answer can be both related to communication as well as being singular nouns.
Maybe there's a link between them I don't understand?

'eccentric coerced us to install old' is the wordplay.
'eccentric' is an anagram indicator.
'to install' indicates putting letters inside.
'old' becomes 'o' (abbreviation as in OT - Old Testament).
'coerced'+'us'='coercedus'
'coercedus' anagrammed gives 'surcecode'.
'surcecode' enclosing 'o' is 'SOURCE CODE'.

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I've seen this clue in The Independent.

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