You can search using any custom field that you have access to just like you would any field code. The only difference is that all custom field codes begin with an underscore, like _DD.OB.PSE2ndopin. The field code is the field name that was created by the person that created the field (be it you or someone on your team). You can find that field code by hovering over the field name in the Custom Field panel, in the Custom Field manager (1), and hovering over the column in the Search Results. 

However, probably the easiest way to search with custom fields is with the Query Builder form. You can start typing the underscore and the custom field code name to find what you're looking for (2).

You may be familiar with the FIELD field code to find empty data fields in any normal AcclaimIP patent data field.  The FIELD field code also works for custom fields.

For example, let's say you define a custom field to categorize patents, and you name it "Technology" and give it a field code _TAX.TECH.  Remember all custom field codes begin with a leading underscore character to prevent user-defined field codes from colliding with AcclaimIP's standard field codes.

FIELD:isEmpty_TAX.TECH  -->  Finds all patents where the _TAX.TECH custom field contains no data.

You'll find that you'll use this query quite often when you want to track the progress of some workflow you designed for you and your group.  

For example, let's say you want to rate and rank your entire portfolio along several dimensions.  You might create custom fields for your rating system, then query the fields for the empty state (or NotEmpty state) to see how many patents are left to rate.

The inverse is also true:

FIELD:isNotEmpty_TAX.TECH  -->  Finds all patents with data in the _TAX.TECH custom data field.

Notice the query uses the FIELD:isNotEmpty switch targeted to the _DD.OB.PSE2ndopin field code (1).  The result are patents which have been tagged with something in that field which you or your administrator created.

In this example, we ran the opposite query and found Google's patents that have not yet been tagged with data in that _DD.OB.PSE2ndopin custom field.  Notice the "isEmpty" (1) switch on the FIELD field code.  All the records have blank (or empty) data in that custom field I defined earlier.