A lot of the properties on world importers/exporters aren't useful and don't make sense. For example, the world block importer's "Pick Up All Item Blocks" has "Check Damage" and "Check NBT", but since it just takes a Boolean, there's nothing to check the damage or NBT against. The same applies to all of the "Predicate" forms that have these properties. Also, the world fluid importer has a "Blacklist" property for "Pick Up All Fluids" and "Pick Up Fluids Predicate" which is similarly nonsensical. ("Pick Up Fluid" also has a "Blacklist" property, which could be interpreted as "pick up every fluid except this one", except that it doesn't currently do this.)