ReadableValue
Corex\Config\Data\ReadableValue · class · Config layer
A stored value as a person reads it. An answer with several choices (a multi-select, a checkbox group) is stored as a list, and a list of plain values is exactly a comma-separated sentence. The Data screen printed it as JSON, ["brand-identity","motion-graphics"], where an operator expected two services; the export had the rule and the screen did not, and a client site carried the difference as a patch. A keyed or nested value keeps its JSON on purpose: joining ['source' => 'newsletter'] would print newsletter and throw away the half that says what it is.