Hi Julio, I can write some Python code that will allow Chimera to read the "TOM toolbox for Electron Tomography" format. Is this format used with other software? Can you provide me an example file? What is the typical file suffix? For an example file you can email me something under 5 Mbytes, or put it on the web or an ftp site for me to download. I don't see any header parameters that indicate xyz pixel sizes in nanometers. This is useful in Chimera if you are for example docking crystal structures. If it isn't available I can just open the data in Chimera with pixel sizes defaulting to 1. I also don't see a field that encodes byte order. The machine coding field (Mac, PC, SGI, ...) is not a good way to deduce byte order, but maybe it is the best info available in the header. I don't understand the comments about "abandoned header". It sounds like this means there is no header on certain files. Chimera won't be able to read those. Tom