IBM documentation of the LIST constructor function contains the following sentence: "The LIST constructor complex function is used to explicitly generate lists of values that can be assigned to fields in an output message".
What does the term "explicitly generate" mean?
I assume you are referring to this topic in the IBM docs for IBM Integration Bus: https://www.ibm.com/docs/en/integration-bus/10.0?topic=functions-list-constructor-function.
You may find it useful to read this topic as well: https://www.ibm.com/docs/en/integration-bus/10.0?topic=functions-row-list-comparisons
In previous versions of IIB/WMB a 'list' was an internal data type (some built-in functions would return a list), but the ESQL programmer could not declare a list or construct a list using their own code.
So to answer your question...I think the phrase 'explicitly generate' is highlighting the fact that it is now possible for a programmer to declare and initialise a literal list of values, and work with that list in their ESQL code.