What works:

  * Print to brother4040 PDF 1.3 files from USB stick
  * Print to brother4570 (any?) PDF files from USB stick

Pending:

  * Print to brother4040 from network
  * Print to brother4570 from network
    + Test which print spool works
  * Print color-managed to brother4570 from network
  * Document how to print
    + Cancel failed/hanging print job in CUPS
  * Document how to color calibrate printer