FieldValueList is an useful feature in the for each ... next loop, but it would also be quite useful in the rest of the script.
Today we can accomplish the same as an FieldValueList function would do by the following script.
FieldValues:
LOAD Concat(Chr(39) & [Field] & Chr(39), ',') as FieldValueList;
LOAD Field FROM SOURCE;
LET vFieldValueList = Peek('FieldValueList',-1,FieldValues);
DROP TABLE FieldValues
It would be easier and more available for all developers if the same output would be available from this command.
LET vFieldValueList = FieldValueList('Field');
As it is available in the for each ... next loop I would guess that it could not big a deal to open up for using it in the rest of the script