Specifies the first part of a string printed by a scanner’s endorser—usually the part before the counter. With most scanners, specifying a prefix is optional. See Endorsing documents as they are scanned.
The maximum length of the endorser text depends on the scanner, but a typical maximum length is 70 characters, including the counter, if any.
With som scanners, you can specify placeholders in the prefix string. Some scanners require that a counter be represented in the prefix by one or more placeholder characters. For more information about prefix strings, please refer to the documentation provided with your scanner.
FYI, if anyone asks for it, there are lots of details on prefix strings in FORMS Help and INVOICES Help that we could easily import to this help project. It would need to be updated as far as which specific scanner models the info applies to.