ORIGINAL NEGATIVE - INTERPOSITIVE COPY NEGATIVE

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4.7.4 - B/W duplicate positives or interpositives
Interpositives used as duplicating stages can be recognised as such only after the early 1920's. Thereafter most interpositives that were intended for duplication only and did not have a dual function were not acceptable as projection prints. Most had negative type [BH] perforations and were visually lower in contrast, with markedly low-density blacks and sometimes grey or coloured bases.

4.7.5 - Colour duplication elements
Prior to the introduction of tripack materials and colour development the duplication stages of colour processes were difficult to identify without detailed knowledge of the process as a whole. However once Kodak had started to introduce colour duplication materials in the 1950's recognising colour intermediates is quite easy.
Initially and until today the most extensively used system uses Eastman Colour Intermediate Film for both stages of duplication, for the preparation of the Interpositive and the duplicate negative.