To download content as needed from the server while playing the game, LEGO introduced a custom segmented file format. The actual files lived in Segmented Data (.sd0) files, while the compression process also generated Segmented Index (.si0) files to be used when creating the Catalog (.pki).
Segmented Data (.sd0)¶
There is a decompressor available, see the Tools section.
Segmented Index (.si0)¶
Not documented yet