One of their very early decisions was extremely good in my opinion. Each blender file is saved with a complete schema at the start which basically describes a b

One of their very early decisions was extremely good in my opinion. Each blender file is saved with a complete schema at the start which basically describes a bunch of C structs, and has a marker for byte order. This means that .blend files can be backwards and forwards compatible, and in the most common case of the schema matching your memory layout, can have their data structures copied directly into memory and then only pointer patching is required. It's quite remarkable.