This carries free-form binary or text parameters passed into whichever foreground diagnostic test is selected, for tests that need extra configuration beyond a simple test ID. Because its contents are test-specific and undocumented in the object's own description, an admin generally only populates this field when following vendor-provided instructions for a particular diagnostic that requires it, rather than guessing at a format. For example, a vendor support engineer instructs the admin to set cardDiagOptionStr to a specific byte sequence to target a particular memory bank during a targeted diagnostic run.