Xerox 6100BD - Phaser Color Laser Printer Fundamentals page 63

Document design
The CMC-7 font consists of 10 numeric characters (0-9), five
special symbols, and 26 alphabetic characters (A-Z). The five
special symbols are illustrated in the following figure:
Figure 4-7. CMC7 special symbols
S-1: Indicates the start of the bank's internal information
(account number, etc.). Although it serves a purpose similar to
the E13B On-Us symbol, it is not used in the CMC7's equivalent
to the E13B Auxiliary On-Us field.
S-2: Identifies the start of the Amount field. Unlike the E13B
structure, this symbol is not used to terminate the Amount field.
The CMC7 Amount field terminates when the appropriate
number of digits (minimum 10, maximum 12, followed by a
blank) have been detected.
S-3: Used as the terminator for the bank routing information. It
also functions as the terminator of the check number field
(following a minimum of four digits, maximum of seven digits).
S-4: Not used. Although its structure is defined, this symbol
usually does not appear in the structure of the MICR line.
Generic MICR Fundamentals Guide 4-17