Since the enactment of Check 21, there has been unprecedented adoption of image exchange. This standard replaces the use of DSTU X9.37 and establishes the basis for U.S. check image exchange involving settlement between two financial institutions. ANS X9.100-180 has been adopted for Canadian internal country exchange. It is only used in the U.S. for specialized applications and is not used for U.S. financial exchange. This standard incorporates fixes and clarifications identified in various industry companion documents associated with DSTU X9.37. It also establishes requirements and limitations that are compatible with current industry practice. However, this standard maintains flexibility in order to accommodate the needs of different institutions and exchange networks. It does not have the extent of flexibility contained in ANS X9.100-180 and is not intended to cover all types of image exchange. Users of this standard should be aware that most financial exchanges utilize a "companion document" that defines the specific requirements and implementation rules for exchange within a particular network or institution agreement. The companion document should reference the specific edition of this standard that applies with the specific version of the companion document in use. This standard, including the normative annexes, establishes the file sequences, record types, and field formats to be used for the electronic exchange of check MICR line, associated check processing data and check images in the form of cash letters. This standard does not address operational, implementation, or settlement issues. These issues may include, but are not limited to, a choice of: data and image compression, encryption, and transmission specifications and data representation. The informative annexes attached to this standard provide information that may prove useful to those planning to implement the standard.