Optional formatFormat hint passed directly to the document parser.
'pdf' | 'docx' | 'md' | 'txt'
Optional signalCancels this read and no other: load rejects with the signal's reason.
officeparser checks the signal between its steps, so a step that reads
one part's markup finishes first; a scan read in a worker thread ends with
its worker. A deadline is a signal made for the read:
AbortSignal.timeout(ms).
Options of one read.