Used to specify that the text in certain fields should be stored in the index in a way that permits unique field values to be enumerated quickly.

DIndexJob Class

When a field is listed in EnumerableFields, all of the values of that field are stored in the index in a way that permits the values to be enumerated using WordListBuilder.ListFieldValues. The field names in the list can contain wildcards (* and ?). A set containing a single entry "*" would match all fields. 

The maximum amount of text that can be stored in each stored field is the lesser of the MaxStoredFieldSize option setting or 127 characters, including the field name. 

All enumerable fields are also automatically designated as stored fields (see StoredFields).

dtsWordListBuilder::listFieldValues Method 

Retrieving Fields in Search Results