This is a REAL problem. The two file solution was raised in the imageNCIF discussions, but nobody favoured it. Even if you manage to overcome the file pointer problem, through names conventions etc. This leaves the possibility for the two to become separated. And if the possibility exists then it WILL happen.
Binary images are portable and are transferred between different computer systems.
With integer data only byte swapping is necessary, and IEEE reals are becoming standard. In fact at present text data is much less standardised than Integer data types. Changes in the future seem more likely to affect character data than integer and floating point data. Multi-byte character sets are presently being developed. Whilst I appreciate your efforts in understanding the problem of mass data storage and transport, I'm afraid that I and I think the large majority of the imageNCIF group will reject your proposal for the reasons given above.