The first step in the ingestion process is to un-zip all compressed files (e.g., ZIP or RAR) and extract files from containers (e.g., PST or MBOX email container). Disco will extract nested containers as far down as they go (i.e. ZIPs within ZIPs within ZIPs, etc.).
Also, DISCO will extract embedded files into separate documents. For example, Disco will extract an Excel file embedded within another Office document, such as a PowerPoint.