...will hand over day-to-day operations and management of the service to CHAPS Clearing Company, which operates the CHAPSsterling high-value same-day payment system. Following the initial launch of the central infrastructure, work is...
http://www.bankingtech.com/bankingtech/article.do?articleid=20001667941
...accepts BACS payments A Office of an agency bank that accepts BACS payments N Does not accept BACS payments 2 CHAPSSterling D Direct Office [that is, CUG member] of a CHAPS GBP Member that accepts CHAPS GBP payments I Indirect Office...
http://jira.iona.com/secure/attachment/14677/TECH_SPEC_BI.pdf