This specification describes the WOSA/XFS service class of check readers and scanners. Check image scanners are treated as a special case of check readers, i.e., image-enabled instances of the latter. This class includes devices with a range of features, from small hand-held read-only devices through which checks are manually swiped one at a time, to much larger devices (i.e., tabletop) which automatically feed checks by the batch past a reader, an encoder, an endorser, an optional image scanner, to be sorted into one of several pockets. The high end device of this class usually found in bank branches shares many capabilities with the still larger devices usually found only in a bank's central data processing site (i.e., high-speed reader/sorters), but the latter are not explicitly addressed here. The specification of this service class includes definitions of the service-specific commands that can be issued, using the WFSAsyncExecute, WFSExecute, WFSGetInfo and WFSAsyncGetInfo functions.
In the U.S., checks are always encoded in magnetic ink for reading by Magnetic Ink Character Recognition (MICR), and a single font is always used. In Europe some countries use MICR and some use Optical Character Recognition (OCR) character sets, with different fonts, for their checks.
In all countries, typical fields found encoded on a check include the bank ID number and the account number. Part of the processing done by the bank is to also encode the amount on the check, usually done by having an operator enter the handwritten or typewritten face amount on a numeric keypad.