Using regular expressions can greatly simplify your BRANCH constructs. The regular expression appendix in the B2B Integrator Guide describes the syntax. The regular expression in a label must be surrounded with slashes. A couple of examples:
Tests for one or more characters. Strings that are $null or are empty will not be selected by this label (e.g. the branch won’t take this path)
Tests that the string starts with the characters “ISA”.
BRANCH on ‘/tailOfAK5’
/.+/: MAP (tailOfAK5 has one or more chars)
$default: SEQUENCE (tailOfAK5 is empty or null)