Patents are divided into many fields, such as inventor name. By narrowing your search so that a document is only counted as a 'Hit' if the term you are searching for occurs in the field you specified, you can greatly decrease the likelihood of having extraneous patents returned.

To make fielded searching easier, we've compiled a list of all the available fields (A list is also available at the bottom of the advanced search page), information about each, and tips on their use. The currently available fields are (in alphabetical order):

• Abstract
• Application Date
• Application Number
• Assignee City
• Assignee Country
• Assignee Name
• Assignee State
• Assistant Examiner
• Foreign Priority
• Foreign References
• Government Interest
• International Class
• Inventor City
• Inventor Country
• Inventor Name
• Inventor State
• Issue Date
• Legal Representative
• Other References
• Patent Number
• Patent Title
• PCT Information
• Primary Examiner
• Reissue Data
• Related U.S. Application Data
• Current U.S. Class/SubClass
• U.S. References

Abstract (ABST)

Definition: The abstract is a brief summary and description of the patented item.
Tips: The abstract contains most of the relevant words of a patent. If you're looking to avoid odd occurrences of a word in the reference section (titles of magazines, etc.) it's good idea to narrow your search to the abstract field.

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Application Date (APD)

Definition: The date the application for the patent was filed.
Tips: Like the other date fields (only issue date currently), you can use one of three formats for your search:

1. <four digit year><two digit month><two digit date>. For example, Jan 1, 1995 would be 19950101.
2. <Month>-<Date>-<Year>.
   Month can be the number of the month, the full name of the month, or an abbreviation thereof (i.e. 1, January or Jan).
   Date must be a number between 1 and 31 or a '*'
   Year must be a four digit year. (i.e. 1996)
   So, a Full date can look like 1-1-1996, Jan-1-1996 or January-1-1996.
3. Just like 2, only use /s instead of -s.
   

You can now search for a range of dates using the -> operator. For example, to search for patents with application dates between January 1, 1995 and Feb 14, 1995, search for APD/1/1/1995->2/14/1995. If you want to search for all patents applied for in January of 1995, it's simpler to search for APD/1/*/1995 than to search for APD/1/1/1995->1/31/1995, though both will return the same results.

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Application Number (APN)

Definition: The application number of the patent.
Tips: Whether you include commas in the application number or not is optional, either way will work.

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Assignee City (AC)

Definition: The city in which the assignee of the patent is located.

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Assignee Country (ACN)

Definition: The country in which the assignee of the patent is located.
Tips: If the patent assignee was inside the U.S., there is no assignee country field. Instead, there is an assignee state (AS) field. Currently, you must search for a country code in this field rather than the full name of the country. See the Country code table for a list of country codes.

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Assignee Name (AN)

Definition: The name of the assignee.
Tips: If the assignee was a person, and you want to search for the full name, you have to format your query like: "last_name; first_name initial". The quotes are essential, since this is a phrase search. For example, to search for patent assigned to John E. Doe, search for AN/"Doe; John E." instead. If the assignee were John E. Doe III, you'd search for AN/"Doe III; John E.".

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Assignee State (AS)

Definition: The U.S. state or territory in which the assignee of the patent is located.
Tips: The state this refers to is the state within the U.S. If the assignee resides outside the U.S., there will be an assignee country (ACN) field instead of an assignee state field. Currently, you must search for a state code in this field rather than the full name of the state. See the State code table for a list of state codes.

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Assistant Examiner (EXA)

Definition: The assistant examiner for the patent.
Tips: Like all other name fields, if you want to search for the full name of the assistant examiner, you have to format your query like: "last_name; first_name initial". The quotes are essential, since this is a phrase search. For example, to search for patents for which John E. Doe was the assistant examiner, search for EXA/"Doe; John E." instead. If the assistant examiner were John E. Doe III, you'd search for EXA/"Doe III; John E.".

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Foreign Priority (PRIR)

Definition: Data indicating in which foreign countries an application claims priority.

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Foreign References (FREF)

Definition: Lists foreign patents cited as references.

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Government Interest (GOVT)

Definition: Contains data describing the Government's Interest in the patent.

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International Class (ICL)

Definition: The International classification(s) the patent has been placed under.
Tips: You can use one of two formats to search in the International Class field:

1. Class-SubClass/SubSubClass
2. "Class SubClass/SubSubClass"

Thus, to search for International Class G06F 19/00, you could either search for ICL/G06F-19/00 or for ICL/"G06F 19/00". Formatting your search in this field in any other way will result in an error.

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Inventor City (IC)

Definition: The city in which the inventor of the patent resides.

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Inventor Country (ICN)

Definition: The country in which the inventor of the patent resides.
Tips: If the inventor resides in the U.S., there is no Inventor Country field. Instead, there is an Inventor State (IS) field. Currently, you must search for a country code in this field rather than the full name of the country. See the Country code table for a list of country codes.

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Inventor Name (IN)

Definition: The inventor(s) of patented item.
Tips: If you want to search for the full name of the inventor, you have to format your query like: "last_name; first_name initial". The quotes are essential, since this is a phrase search. For example, to search for patent invented by John E. Doe, search for IN/"Doe; John E." instead. If the inventor were John E. Doe III, you'd search for IN/"Doe III; John E.".

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Inventor State (IS)

Definition: The U.S. state the inventor resides in.
Tips: If the inventor resides outside the U.S., there is no inventor state field. Instead, there is an Inventor Country (ICN) field. Currently, you must search for a state code in this field rather than the full name of the state. See the State code table for a list of state codes.

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Issue Date (ISD)

Definition: The date the patent was officially issued.
Tips: Like the other date fields (only application date currently), you can use one of three formats for your search:

1. <four digit year><two digit month><two digit date>. For example, Jan 1, 1995 would be 19950101.
2. <Month>-<Date>-<Year>.
   Month can be the number of the month, the full name of the month, or an abbreviation thereof (i.e. 1, January or Jan).
   Date must be a number between 1 and 31 or a '*'
   Year must be either a four digit year. (i.e. 1996)
   So, a Full date can look like 1-1-1996, Jan-1-1996 or January-1-1996.
3. Just like 2, only use /s instead of -s.
   

You can now search for a range of dates using the -> operator. For example, to search for patents with issue dates between January 1, 1995 and Feb 14, 1995, search for ISD/1/1/1995->2/14/1995. If you want to search for all patents issued in January of 1995, it's simpler to search for ISD/1/*/1995 than to search for ISD/1/1/1995->1/31/1995, though both will return the same results.

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Legal Representative (LREP)

Definition: The legal representative of the patent filer
Tips: If you want to search for the full name of a legal representative, you have to format your query like: "last_name; first_name initial". The quotes are essential, since this is a phrase search. For example, to search for patent where John E. Doe is listed as the legal representative, search for LREP/"Doe; John E." instead. If the legal representative were John E. Doe III, you'd search for LREP/"Doe III; John E.".

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Other References (OREF)

Definition: Lists other references cited as prior art.

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Patent Number (PN)

Definition: The number of the patent.
Tips: There are several things to remember about patent number searches.

1. Non-utility patents have prefixes. That is, design patent #123,456 is actually patent D123,456. The prefixes are: 'D' for design patents, 'PP' for plant patents, 'RE' for reissue patents, 'T' for defensive documents, and 'H' for SIRs.
2. Whether you include commas in your search term is optional. The search will work either way.

Note: You must be searching the database which contains the patent you are looking for for this search to work. If you are unsure of what year a patent was issued, see the Database Status page to look up the year, or just search all the years at once by clicking 'All' button in the Select Database list.

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Patent Title (TTL)

Definition: The title of the patent.

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PCT Information (PCT)

Definition: PCT Information related to the patent.
Includes: PCT Number, PCT 371 Date, PCT 102(e) Date, PCT Filing Date, PCT Publication Number, PCT Publication Date.

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Primary Examiner (EXP)

Definition: The primary examiner for the patent.
Tips: Like all other name fields, if you want to search for the full name of the primary examiner, you have to format your query like: "last_name; first_name initial". The quotes are essential, since this is a phrase search. For example, to search for patents for which John E. Doe was the primary examiner, search for EXP/"Doe; John E." instead. If the primary examiner were John E. Doe III, you'd search for EXP/"Doe III; John E.".

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Reissue Data (REIS)

Definition: Data describing the reissue of a patent.
Includes: Application Number, Application Filing Date, Patent Number, Issue Date.

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Related U.S. Application Data (RLAP)

Definition: Parent case and continuation data of prior applications related to the patent.

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Current U.S. Class/SubClass (CCL)

Definition: The current main or cross-reference U.S. Classification the patent items has been placed under. This includes any changes to the issued classification of the patent resulting from reclassification of the technology groupings containing the patent.
Tips: If you are searching for a specific class and subclass, just phrase your term as class/subclass.sub-subclass. Not all classes include a sub-subclass. It's not necessary to include a '.00' as a sub-subclass, even if it is listed that way in the classifications list. If you want your search to match all sub-subclasses, just search for class/subclass.*

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U.S. References (REF)

Definition: Previous U.S. patents cited as prior art.
Tips: If you want to search for a reference to a particular patent, just search for that patent #, with no commas, and specify this field. For example, searching for 'ref/5096294' will return all patents that reference patent #5,096,294, but not that patent itself.

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