Thanks, Terry.
That clears it up.
One wonders what the Yugoslavian delegation to ST52 was thinking, because as well as those channel E1 allocations, there were other Band I and Band III allocations for Yugoslavia using the standard 7 MHz System B channels. The 6 MHz channel E1 would have been suitable for what became System N, but it seems very unlikely that there were plans to use both systems. Most likely they were expecting or at least hoping that Band I would be extended downwards to 40 MHz, a possibility suggested by Kerkhof & Werner, so allowing channel E1 to be expanded to 7 MHz. But that did not happen.
These attachments show the pertinent pages from ST52, with those Yugoslav allocations, and ST61, without:
Cheers,