Each dataset has more possible search fields than are visible with the Select Search Fields button. To read more on Search Fields, visit the Manual Query Using Select Search Fields Button Tutorial. Additionally, you may want to search multiple fields for exact data in each field, which is not possible when selecting from a list of search field options. This is possible, however, using iSearch Analytics's powerful new feature, Search Assist, to build a custom query. Learn more about how to use Search Assist.
Alternatively, you can manually type or copy/paste custom fields into the search bar to build your custom query. This would perform the same actions as building a query in Search Assist. Below is an example of a query specifying where to search for two different terms, and remove terms found in the abstract which meet your criteria:
title:GTP* NOT abstract:Signaling
Therefore, Custom Fields can be used to create a complex search and expand your search options. As you can see in the example above, Custom Fields are typed into the search bar along with the text you wish to find.
Custom Fields will override any options that may be selected in Search Fields (unless you have additional terms that are not directly associated with a field name). There is specific syntax (capitalization, abbreviations, colons, etc.) that must be used in Custom Fields. To learn more about the specific fields you can query and how to format the text, see the Custom Fields user guide section for each dataset: