TransactionSearchAdvanced

With the new NetSuite release, I'm confused as to how to search for a transaction using a TransactionSearchAdvanced. In particular, I'm confused on how to construct a TransactionSearchRowBasic. All I want to do with the TransactionSearchRowBasic is have it return only transactions that are invoices, however I don't know what to do with the SearchColumnEnumSelectField to indicate the type attribute. This is my code so far :

TransactionSearchAdvanced search = new TransactionSearchAdvanced();
TransactionSearchRowBasic basicSearch = new TransactionSearchRowBasic();

// only search for transactions that are invoices
List<SearchColumnEnumSelectField> select = new List<SearchColumnEnumSelectField>();
                   
SearchColumnEnumSelectField one = new SearchColumnEnumSelectField();

I want to create a SearchColumnEnumSelectField, add that to the List, and then turn the list into an array and assign it to basicSearch.type, but the SearchColumnEnumSelectField is unintuitive and pretty different from the way the type field was used previously.