How make an ecw with different information to different scales?

I don't think that's possible in the ECW format.

Dont think this is possible. Where are you going to use this data? In an online mapping portal or as a regular file on a disk?

Hi, Yes we have this done in the web with different tiles, but now I would like to have a single file to use with desktop applications. And i think i have seen an ecw with multiple information at different scales.

Which desktop application? I suspect that the Desktop application itself "switches" between two or more different ECWs at different scales - however it would be very nice if I was wrong. Havent found anything on Google yet.

What SigTill suggests is correct, its common practice to display rasters with different scale information, by setting the visibility scales per raster.

Yes, i already know. That's a valid option but I would like to make it With a single ecw file to to simplify the use and avoid configurating the aplications. In fact, I have already the diferents files at diferents scales. The key it's to know if its posible with the ecw format. Thank you anyway

I would suggest to contact ERDAS/Intergraph or whatever name they have changed to :) directly. Please post the answer here when you find it, although I would bet a beer that the answer is no: http://geospatial.intergraph.com/Homepage.aspx

Surely it is not possible (sorry for the beer), but It could be a great quality for the ecw format. If I get an answer I'll post it.