Boolean to indicate that the uploaded PDF attachment should be used as the visual component
when generating a hybrid PDF (such as a ZUGFeRD document) or any legal PDF representation.
When set to true, this attachment will be considered the legal PDF to display or embed,
instead of regenerating one from the invoice data. It can be used both for PDF deliveries
and for embedding XML (e.g., ZUGFeRD) into the provided PDF.
NOTICE: If the invoice is modified after this PDF has been uploaded, the attachment will still be used as-is, unless explicitly replaced.
B2Brouter treats it as the legal representation provided by the account.
