The United States Patent and Trademark Office (USPTO) plays a crucial role in examining patent applications and granting patents. A patent grants the holder exclusive rights for a specific period to prevent others from making, using, selling, or importing the invention into the U.S. While the USPTO decides whether to grant a patent, enforcing these rights is the patent holder’s responsibility.
This guide provides essential information on A Guide To Filing A Utility Patent Application. Preparing a patent application can be intricate, and consulting a registered patent attorney or agent is highly recommended. Further information can be found:
- By calling the USPTO’s Contact Center at 800-PTO-9199 (800-786-9199) or 571-272-1000.
- On the USPTO website at www.uspto.gov.
- At your nearest Patent and Trademark Resource Center (PTRC). PTRC information is available at the end of this guide.
Patents can be categorized into utility, design, and plant patents. Utility and plant patent applications are further divided into provisional and nonprovisional. A provisional application quickly secures a U.S. filing date, which can be claimed later in a nonprovisional application. It is not examined and is automatically abandoned after 12 months. To benefit from the provisional application’s filing date, a corresponding nonprovisional application must be filed within this period. A patent examiner reviews nonprovisional applications, and if all patentability requirements are met, a patent may be issued. The USPTO receives over 600,000 patent applications annually, with nonprovisional utility patent applications being the most common.
This guide focuses on assisting you in filing your nonprovisional utility patent application, outlining the necessary components and relevant forms available on the USPTO website (www.uspto.gov). The information is derived from patent laws and regulations found in Title 35 of the United States Code (U.S.C.) and Title 37 of the Code of Federal Regulations (CFR), as well as the Manual of Patent Examining Procedure (MPEP), all accessible on the USPTO website, at PTRCs, and in most law libraries.
For questions about other types of patent applications, locating a patent attorney or agent, obtaining the most recent fee schedule, or acquiring copies of other USPTO publications, contact the USPTO’s Contact Center, visit the USPTO’s website, or visit a PTRC.
Nonprovisional Utility Patent Filing Options
Nonprovisional utility patent applications can be submitted to the USPTO via the Patent Center electronic filing system, U.S. mail, or hand delivery to the Office in Alexandria, Virginia. Utility applications represent the vast majority of patent applications filed at the USPTO.
Important Update: As of November 15, 2011, applications filed by mail or hand delivery incur an additional $400 fee, termed the “non-electronic filing fee.” This fee is reduced by 50% to $200 for applicants qualifying for small entity status (37 CFR § 1.27(a)) or micro entity status (37 CFR 1.29(a) or (d)). To avoid this additional fee, file your nonprovisional utility application electronically through Patent Center. (Reissue, design, plant, or provisional applications are exempt from this fee.)
Patent Center is a user-friendly, web-based system that enables anyone with internet access to file patent applications without specific software or document preparation changes. It replaced the former EFS-Web system. Patent Center streamlines the process by allowing the submission of the complete specification, including the description, claims, and abstract, as a single DOCX file. The following section on “Application Requirements” details the significance of this change. More information is available at the Patent Center. For technical support, contact the Patent Electronic Business Center at 866-217-9197, Monday through Friday, 6 a.m. to 12 midnight Eastern Time, excluding federal holidays.
Application Requirements for a Utility Patent
A nonprovisional utility patent application must be in English, or accompanied by an English translation, a statement verifying the translation’s accuracy, and the fee specified in 37 CFR § 1.17(i). Failure to provide the translation, statement, or fee will result in a notice allowing the applicant to submit the missing items within a specified timeframe.
A complete application must include a specification (description and claims), necessary drawings, an oath or declaration, and the required filing, search, and examination fees.
Patent Center supports electronic documents in DOCX format. The entire specification (description, claims, and abstract) can be created using common word processing software like Microsoft® Word, Google Docs, Office Online, LibreOffice and Pages for Mac, or Corel® WordPerfect.
Important Change: Starting January 17, 2024, all descriptions, claims, and abstracts for nonprovisional utility patent application specifications must be filed in DOCX format. Failure to do so will result in a $400 fee, reduced to $160 for small entity applicants and $80 for micro entity applicants (37 CFR § 1.16(u)). This fee applies if any part of the specification (written description, claims, or abstract) does not meet the USPTO’s DOCX requirements. Other application documents, like drawings and signed declarations, can be scanned and submitted as PDF files. Note that this additional fee does not apply to reissue, design, plant, and provisional applications.
Applicants who are used to filing patent application specifications in PDF format must transition to DOCX format for all nonprovisional utility patent applications filed on or after January 17, 2024, to avoid the extra fee. This also includes continuing and divisional applications, as well as applications claiming benefit from a previously filed provisional application.
For detailed information, see “File patent application documents in DOCX” at File patent application documents in DOCX.
Each document must adhere to specific margin requirements: at least 2 cm (3/4 inch) top, 2.5 cm (1 inch) left, 2 cm (3/4 inch) right, and 2 cm (3/4 inch) bottom. Pages must be numbered consecutively, starting with page one, located centrally above or below the text. DOCX document size should be 8.5 x 11 inches (standard) or 21 x 29.7 cm (DIN size A4). The specification, including the description, claims, and abstract, must be 1.5 or double-spaced in a single column of text, using a nonscript font (e.g., Arial, Times Roman, or Courier), preferably in 12-point font size.
A complete nonprovisional utility patent application should include the following elements, arranged in the order presented below:
- Utility Patent Application Transmittal Form or Transmittal Letter
- Appropriate Fees
- Application Data Sheet (see 37 CFR § 1.76)
- Specification (including the description, at least one claim, and an abstract)
- Drawings (when necessary)
- Executed Oath or Declaration
- Nucleotide and Amino Acid Sequence Listing (when necessary)
- Large Tables or Computer Listings (when necessary)
The following sections provide detailed descriptions of these elements.
Utility Patent Application Transmittal Form or Transmittal Letter
A Utility Patent Application Transmittal Form (Form PTO/AIA/15) or a transmittal letter must accompany every patent application. It identifies the filed items, such as the specification, drawings, and declaration, along with the first named inventor, application type, invention title, application contents, and any accompanying enclosures. For correspondence after the initial filing, use Form PTO/SB/21.
Appropriate Fees for a Utility Patent
Filing, search, and examination fees can be paid electronically via credit card or electronic funds transfer. Paying these fees online when filing via Patent Center is recommended to avoid a late surcharge of $160 ($64 for small entity applicants and $32 for micro entity applicants), which is incurred if these fees or the required oath or declaration are filed after the application filing date.
While paper filing (mail or hand-delivery) is possible, it incurs a non-electronic filing fee of $400 ($200 for small and micro entities) in addition to the standard fees. Furthermore, failing to file the specification, claims, and abstract in DOCX format for applications filed on or after January 17, 2024, will also trigger an additional fee as outlined in 37 CFR § 1.16(u). If filing in paper, the Fee Transmittal Form (Form PTO/SB/17) can be used to calculate the necessary fees and indicate the method of payment (check, money order, USPTO deposit account, or credit card).
If paying by check or money order, make it payable to the “Director of the United States Patent and Trademark Office.” Applications filed without the required fees will result in a notification requiring submission of the fees plus the late surcharge within a specified period.
Electronic filings exceeding 133 pages (specification and drawings) will incur an application size fee. Paper filings exceeding 100 pages also require this fee. Excess claim fees are also assessed for applications with more than three independent claims or more than 20 total claims.
Always consult the current fee schedule before filing, as fees are subject to change, typically in October each year.
Fee Discounts Based on Small or Micro Entity Status
Qualifying small entities (37 CFR § 1.27(a)) receive a 60% reduction in filing, searching, examining, issuing, appealing, and maintaining fees. Micro entities meeting the requirements of 37 CFR § 1.29(a) or (d) receive an 80% reduction.
The non-electronic filing fee for paper filings is reduced by 50% (to $200) for small and micro entities. Filing electronically via Patent Center is the only way to completely avoid the $400 non-electronic filing fee.
Application Data Sheet (ADS)
Submitting an application data sheet (ADS) is standard practice for nonprovisional applications and is mandatory in certain situations. For applications filed on or after September 16, 2012, domestic benefit claims and foreign priority claims must be made in an ADS within four months of filing or 16 months from the filing date of the prior application, whichever is later. See 37 CFR § 1.78 for domestic benefit claims and 37 CFR § 1.55 for foreign priority claims. Form PTO/AIA/14 is the USPTO’s ADS form for utility applications. Refer to 37 CFR § 1.76 and MPEP § 601.05 for further details.
A corrected ADS can be filed to rectify or update information in a previously filed ADS. Even if an ADS was not initially filed, a corrected ADS is required to modify existing information. The corrected ADS must use underlining to indicate inserted information and strike-through text or brackets to indicate removed information. However, some information requires compliance with specific rules for changes. For example, changes to named inventors must adhere to 37 CFR § 1.48, correspondence address changes to 37 CFR § 1.33(a), and foreign priority/domestic benefit information changes to 37 CFR §§ 1.55 and 1.78, respectively.
Specification of the Invention
The specification includes a detailed written description of the invention, outlining the manner and process of making and using it. This section concludes with the claims, which must start on a new page. The description must be clear, full, concise, and exact, enabling a person skilled in the relevant art to make and use the invention.
For inventions involving computer programming, program listings can be included as part of the specification (37 CFR § 1.96(b) and (c)). Specification pages (excluding transmittal letters and other forms), including claims and the abstract, must be numbered consecutively, starting with 1, centered above or preferably below the text (except for reissue applications or reexamination proceedings). Lines must be 1.5 or double-spaced (lines not part of the specification need not be). Indenting each new paragraph and numbering paragraphs (e.g., [0001], [0002], [0003], etc.) is recommended.
For inventions made with U.S. government support, 35 U.S.C. 202(c)(6) and 37 CFR 401.14(f)(4) require a statement acknowledging this support and the government’s rights. For example: “This invention was made with government support under [IDENTIFY THE CONTRACT] awarded by [IDENTIFY THE FEDERAL AGENCY]. The government has certain rights in the invention.”
Using the following section headings is preferable for structuring the description portion of the specification. Section headings should be in uppercase without underlining or bold type. If a section is not applicable, state “Not Applicable” after the heading.
Title of Invention
The invention’s title (or an introductory section stating the name, citizenship, residence of each applicant, and the title) should appear as the heading on the first specification page. While titles can be up to 500 characters, they should be as short and specific as possible.
Cross-Reference to Related Applications
For applications filed after September 16, 2012, claiming benefit from prior-filed applications (nonprovisional or international designating the U.S.) under 35 U.S.C. §§ 120, 121, or 365(c), or from a provisional application under 35 U.S.C. § 119(e), the reference to the earlier application must be in an application data sheet (37 CFR § 1.76). See 37 CFR § 1.78. Cross-references to other related patent applications can be included in an initial description section, if appropriate.
Statement Regarding Federally Sponsored Research or Development (if Applicable)
This section should state any rights to inventions made under federally sponsored research and development. See MPEP §310 for details.
Reference to a Sequence Listing, a Large Table, or a Computer Program Listing Appendix on Read-Only Optical Disc (if applicable)
Material submitted separately on a read-only optical disc requires a specific incorporation by reference statement in the specification. Only computer program listing appendixes, sequence listings for nucleotides/amino acids, and large tables are accepted on read-only optical discs. This information must comply with 37 CFR § 1.52(e), and the specification must reference the disc and its contents. The disc’s files must be in standard ASCII character and file formats, unless it’s a sequence listing XML (applications filed on/after July 1, 2022). The specification must specify the number of read-only optical discs and the files on each disc.
Computer program listings exceeding 300 lines (up to 72 characters per line) must be submitted on a read-only optical disc (37 CFR § 1.96), with an incorporation by reference statement in the specification. Shorter listings are optional for read-only optical disc submission. The computer program listing appendix will not be printed with any patent or patent application publication.
Sequence listings exceeding the electronic filing system limits can be provided on a read-only optical disc (37 CFR §§ 1.821-1.825 for applications filed before July 1, 2022, or 37 CFR §§ 1.831-1.835 for applications filed on/after July 1, 2022), and require an incorporation by reference statement in a separate paragraph.
Large tables exceeding 50 pages on paper can be submitted on a read-only optical disc (37 CFR § 1.58) with an incorporation by reference statement. Data in large tables must align visually with rows and columns.
Background of the Invention
This section should define the field of endeavor to which the invention belongs. It can also paraphrase relevant U.S. patent classification definitions or the subject matter of the claimed invention.
Include information known to you, citing specific documents related to your invention. If applicable, reference specific problems in the prior art that your invention addresses. See MPEP § 608.01(c) for more information.
Brief Summary of the Invention
This section should summarize the substance or general idea of the claimed invention. It can highlight the invention’s advantages and how it solves existing problems (preferably identified in the Background of the Invention section). A statement of the invention’s object may also be included. See MPEP § 608.01(d) for details.
Brief Description of the Several Views of the Drawing
If drawings are included, this section must list each figure by number (e.g., Figure 1A) with corresponding explanations of what each figure depicts.
Detailed Description of the Invention
This is the most crucial section of the description, requiring a full, clear, concise, and exact explanation of the invention and the process of making and using it. This section should differentiate the invention from others and from existing technology. It should completely describe the process, machine, manufacture, composition of matter, or improvement invented. For improvements, the description should focus on the specific improvement and parts that cooperate with it or are necessary for understanding the invention.
The description must enable a person of ordinary skill in the art to make and use the invention without extensive experimentation. The best mode contemplated by the inventor for carrying out the invention must be described. Each element in the drawings should be mentioned in the description. See MPEP § 608.01(g) for further information.
Claim or Claims for a Utility Patent
The claims must precisely define the subject matter that the inventor(s) regard as the invention. They determine the scope of patent protection. The grant of a patent largely depends on the scope of the claims.
A nonprovisional utility patent application requires at least one claim. The claim(s) section must start on a separate page. Multiple claims must be numbered consecutively with Arabic numerals.
Claims can be presented in dependent form, referencing and further limiting another claim(s). Dependent claims should be grouped with the claim(s) they refer to whenever possible. Multiple dependent claims referring to more than one claim must refer to them in the alternative only. Each claim should be a single sentence. Elements or steps within a claim should be separated by line indentation.
Abstract of the Disclosure
The abstract helps the USPTO and the public quickly understand the technical disclosures of the invention. It highlights what is new in the relevant art. The abstract should be in narrative form, limited to a single paragraph, and must begin on a separate page. It should not exceed 150 words. See MPEP § 608.01(b) for more details.
Alt Text: Example of a drawing for a utility patent application, showcasing proper numbering, reference characters, and lead lines as per USPTO guidelines.
Drawings Necessary for a Utility Patent
A patent application must include drawings if they are necessary to understand the invention. Most applications include drawings that show every feature specified in the claims. Introducing a drawing essential to understanding the invention after the filing date is prohibited due to the rule against adding new matter. See the “Drawing Requirements” section for detailed information.
Oath or Declaration
An oath or declaration is a formal statement required from the inventor in nonprovisional applications (utility, design, plant, and reissue). Use Form PTO/AIA/01 or PTO/AIA/08 for utility applications. Form PTO/AIA/01, filed with an application data sheet, is preferred. Each inventor must sign an oath or declaration containing statements required by law and USPTO rules, affirming their belief in being the original inventor or a joint inventor of the claimed invention, and stating that the application was made or authorized by them (35 U.S.C 115 and 37 CFR § 1.63). An oath must be sworn before a notary public, while a declaration does not require notarization. Oaths/declarations are required for design, plant, utility, and reissue applications. In addition to the required statements, the inventor’s legal name, mailing address, and residence (if not in the application data sheet) must be included.
Instead of an oath or declaration, a substitute statement can be signed by the applicant for inventors who are deceased, legally incapacitated, cannot be found/reached after diligent effort, or refuse to execute the oath/declaration. Joint inventors who are the applicant can sign for an inventor who cannot be found/reached or refuses to sign, but not for deceased or legally incapacitated inventors. A legal representative of a deceased/incapacitated inventor or the assignee can sign for them. The assignee (or party to whom the inventor must assign the invention) can sign for an inventor who is deceased, incapacitated, cannot be found, or refuses to sign. Form PTO/AIA/02 is the USPTO’s substitute statement form for these situations. When filing a continuing application, a copy of the oath/declaration from the earlier application can be used if it complies with the rules in effect for the continuing application (applications filed on/after September 16, 2012). The oath/declaration must be personally signed by the inventor, either handwritten or with an “S-signature” (typed name or electronic image of a signature between forward slashes). The inventor’s legal name is required.
The oath/declaration must be in a language the inventor understands. If it’s in a language other than English and not a USPTO form or compliant with Patent Cooperation Treaty (PCT) Rule 4.17(iv), an English translation and a statement confirming its accuracy are required. The USPTO provides translations of forms PTO/AIA/01 and PTO/AIA/02 in Chinese (simplified), Dutch, French, German, Italian, Japanese, Korean, Russian, Swedish, and Spanish.
Sequence Listing for a Utility Patent (if applicable)
This section for disclosing a nucleotide or amino acid sequence should list the sequence according to 37 CFR §1.821 through 37 CFR §1.825, in either paper or electronic form.
Obtaining a Receipt for Documents Mailed to the USPTO
Patent correspondence filed in a nonprovisional utility application after the filing date (follow-on correspondence) can still be filed by mail or hand-delivery without incurring the $400 non-electronic filing fee. However, only registered eFilers can file follow-on correspondence via Patent Center. Unregistered eFilers must send it by mail or hand-deliver it. If you receive a “Notice of Incomplete Application” stating an application number was assigned but no filing date granted, you must become a registered eFiler and reply via Patent Center to avoid the $400 fee. Learn to become a registered eFiler at our Getting Started guide or call the Electronic Business Center at 866-217-9197.
A receipt for documents mailed or hand-delivered can be obtained by attaching a stamped, self-addressed postcard to the first page of the documents. The postcard should list each document type and the number of pages. The USPTO will compare the list to the delivery’s contents, note any discrepancies, initial and date stamp the postcard, and return it by mail.
The returned postcard serves as proof of receipt of all listed items, unless noted otherwise by the USPTO. If the postcard is annotated indicating a paper was not received, it won’t serve as evidence of its receipt. Similarly, it won’t prove receipt of inadequately itemized papers.
The postcard’s list of documents should include:
- application number (if known)
- confirmation number (if known)
- filing date (if known)
- title of the invention
- inventor name(s)
It should also include a detailed list of every document type and the number of pages for each.
While electronic filing via Patent Center is highly recommended to avoid the non-electronic filing fee, paper filing is still possible (with the additional $400 fee, $200 for small entities). A postcard submitted with a paper application should include the following:
- title and page count of each USPTO form
- number of specification pages (excluding claims)
- number of claims and claim pages
- number of drawing figures and drawing sheets
- indication of oath/declaration inclusion and page count
- type and number of other documents and their page counts
- payment amount and method (check, credit card, money order, or USPTO deposit account)
Each application component should be itemized. A general statement like “complete application” or “patent application” or “drawings” won’t suffice if a required item is later found missing.
The USPTO will stamp the postcard with the receipt date and application number before returning it. Upon receipt, promptly review the postcard to ensure all documents and pages were received by the USPTO.
According to 35 U.S.C. 21 and 37 CFR § 1.10, correspondence delivered via “Priority Mail Express Post Office to Addressee” service of the USPS is considered filed on the deposit date with the USPS, as shown on the mailing label. If the USPS deposit date is unclear, the Office’s receipt date will be the filing date. Before depositing an application via Priority Mail Express, put the mailing label number on the application papers. Only one application should be mailed per package.
Drawing Requirements for Utility Patents
Drawing requirements are primarily based on 37 CFR § 1.84.
Black and white drawings are typically required, using India ink or its equivalent to create solid black lines. Hand-drawn drawings should be scanned into PDF format for filing via Patent Center. The following margins are required:
- On 21.6 cm x 27.9 cm (8 1/2 x 11 inches) sheets: at least 2.5 cm (1 inch) top, 2.5 cm (1 inch) left, 1.5 cm (5/8 inch) right, and 1 cm (3/8 inch) bottom, leaving a usable surface no greater than 17.6 cm x 24.4 cm (6 15/16 x 9 5/8 inches).
- On 21 cm x 29.7 cm (DIN size A4) sheets: at least 2.5 cm (1 inch) top, 2.5 cm (1 inch) left, 1.5 cm (5/8 inch) right, and 1 cm (3/8 inch) bottom, leaving a usable surface no greater than 17 cm x 26.2 cm.
Numbering of Sheets of Drawings and Views
Drawing sheets should be numbered consecutively with Arabic numerals, starting with 1, within the usable surface. Place numbers in the middle of the top of the sheet, but not in the margin. If the drawing is too close to the top edge, place the numbers on the right-hand side. The sheet numbering must be clear and larger than reference characters to avoid confusion. Indicate the sheet number by two Arabic numerals on either side of an oblique line, showing the sheet number and the total number of sheets.
Views must be numbered consecutively with Arabic numerals, starting with 1, independent of the sheet numbering and in order of appearance. Partial views forming a complete view should be identified by the same number followed by a capital letter. View numbers must be preceded by “FIG.” If only a single view illustrates the claimed invention, it should not be numbered, and “FIG.” should not appear.
Numbers and letters identifying views must be simple, clear, and not enclosed in brackets, circles, or quotation marks. View numbers must be larger than reference characters.
Reference Characters in Utility Patent Drawings
Reference characters not mentioned in the description should not appear in the drawings, and vice versa. Reference characters (preferably numerals), sheet numbers, and view numbers must be plain, legible, and not enclosed in brackets or inverted commas. They should be oriented the same way as the view to avoid rotating the sheet and should follow the object’s profile.
Reference characters must be at least 0.32 cm (1/8 inch) in height and should not interfere with the drawing’s comprehension by crossing or mingling with lines or being placed on hatched or shaded surfaces. To indicate a surface or cross-section, underline the reference character, leaving a blank space in the hatching or shading for clarity.
The same part in different views must always be designated by the same reference character, which must never be used for different parts.
Lead Lines and Arrows
Lead lines connect reference characters to the details they refer to. They can be straight or curved, should be as short as possible, originate near the reference character, and extend to the indicated feature. Lead lines must not cross each other. Lead lines are required for each reference character, except those indicating a surface or cross-section. These characters should be underlined to show that a lead line wasn’t omitted by mistake. Lead lines must be executed like other lines in the drawing.
Arrows can be used at the ends of lines with clear meanings:
- A freestanding arrow on a lead line indicates the entire section toward which it points.
- An arrow touching a line indicates the surface shown by the line, looking in the arrow’s direction.
- To show the direction of movement.
Identification of Utility Patent Drawings
Identifying indicia should include the invention’s title, inventor’s name, application number (if known), and docket number (if any). This information must be within the top margin of each drawing sheet. The name and phone number of a contact person can be provided if the drawings are filed in paper form.
Graphic Forms
Chemical or mathematical formulas, tables, computer program listings, and waveforms can be submitted as drawings, subject to the same requirements. Each formula must be labeled as a separate figure, using brackets to show proper integration. Electrical signal waveforms should be presented as a single figure with a common vertical axis and time along the horizontal axis, identified with separate letters next to the vertical axis. These may be in landscape orientation if necessary. Characters used in formulas and tables must meet 37 CFR §1.58(c) requirements.
Views in Utility Patent Drawings
Drawings must contain as many views as necessary to show the invention, including plan, elevation, section, or perspective views. Detailed views of element portions, enlarged if needed, can also be used. All views must be grouped and arranged on the sheets without wasting space, preferably upright, clearly separated, and not included with specifications, claims, or the abstract. Views must not be connected by projection lines or contain center lines. Waveforms can be connected by dashed lines to show relative timing.
Exploded Views
Exploded views, with separated parts embraced by a bracket, are permissible to show the relationship or assembly order. If an exploded view is on the same sheet as another figure, it should be placed in brackets.
Partial Views in Utility Patent Drawings
A large machine or device can be broken into partial views on a single sheet or extended over several sheets if there is no loss of understanding. Partial views on separate sheets must be capable of being linked edge to edge, with no partial view containing parts of another. Include a smaller-scale view showing the whole and indicating the positions of the parts shown. If a portion of a view is enlarged for magnification, both the view and the enlargement must be labeled as separate views.
Where views on multiple sheets form a single complete view, they must be arranged so that the complete figure can be assembled without concealing any part of any view.
A long view can be divided into parts placed one above the other on a single sheet, but the relationship between the parts must be clear.
Sectional Views
The plane on which a sectional view is taken should be indicated by a broken line on the view from which the section is cut, with ends designated by Arabic or Roman numerals corresponding to the view number of the sectional view, and arrows indicating the direction of sight. Hatching must indicate section portions of an object, made by regularly spaced oblique parallel lines spaced sufficiently apart to be distinguished. Hatching should not impede the reading of reference characters and lead lines. If necessary, hatching can be broken off where reference characters are inserted. Hatching must be at a substantial angle to surrounding axes or principal lines, preferably 45 degrees.
A cross-section must show all materials as they appear in the view from which it was taken. The parts in cross-section must show proper material(s) by hatching with regularly spaced parallel oblique strokes, with the space between strokes chosen based on the total area to be hatched. Various parts of the same item should be hatched identically and accurately indicate the nature of the material(s) illustrated.
Hatching of juxtaposed elements must be angled differently. For large areas, hatching can be confined to an edging drawn around the entire inside of the outline of the area. Different hatching types should have conventional meanings regarding the material’s nature in cross-section.
Alternate Position
A moved position can be shown by a broken line superimposed on a suitable view if it’s not crowded; otherwise, use a separate view.
Modified Forms
Modified forms of construction must be shown in separate views.
Arrangement of Views
One view must not be placed upon another or within another’s outline. All views on the same sheet should face the same direction and be readable when the sheet is upright. If views wider than the sheet are necessary, the sheet can be turned on its side with the top on the right, using the top margin as the heading space. Words must appear horizontally, left-to-right, when the page is upright or turned, except for graphs using standard scientific convention for the axes.
Front Page View
One view should be suitable for inclusion on the front page of the patent application publication and patent as the illustration of the invention.
Scale
The drawing’s scale must be large enough to show the mechanism without crowding when reduced to two-thirds size in reproduction. Indications like “actual size” or “scale 1/2” are not permitted.
Character of Lines, Numbers, and Letters
All drawings must be made using a process that gives them satisfactory reproduction. Every line, number, and letter must be durable, clean, black (except for color drawings), sufficiently dense and dark, and uniformly thick and well-defined. The weight of all lines and letters must be heavy enough for adequate reproduction. This requirement applies to all lines, shading, and lines representing cut surfaces in sectional views. Lines and strokes of different thicknesses can be used if they have different meanings.
Shading
Shading is encouraged to aid understanding if it doesn’t reduce legibility. It’s used to indicate the surface or shape of spherical, cylindrical, and conical elements and can be used lightly on flat parts. This is preferred for parts shown in perspective, but not for cross-sections (see sectional views above). Spaced lines for shading are preferred. These lines must be thin, few in number, and contrast with the rest of the drawings. As a substitute for shading, heavy lines can be used on the shade side of objects, except where they superimpose or obscure reference characters. Light should come from the upper left corner at a 45-degree angle. Surface delineations should preferably be shown by proper shading. Solid black shading areas are not permitted, except for bar graphs or color.
Symbols
Graphical drawing symbols can be used for conventional elements. The elements for which these symbols are used must be identified in the specification. Known devices should be illustrated by universally recognized symbols accepted in the art. Non-universally recognized symbols can be used if approved by the USPTO and not likely to be confused with existing symbols.
Legends
Legends can be used, or required by the examiner, for understanding the drawing, subject to USPTO approval. They should be as concise as possible.
Copyright or Mask Work Notice
A copyright or mask work notice can appear in the drawing, but it must be within the drawing’s sight, below the figure representing the copyright/mask work material, and limited to letters 0.32 cm to 0.64 cm (1/8 to 1/4 inches) high. The notice must be limited to legal elements. For example, “©1983 John Doe” (17 U.S.C. 401) and “M John Doe” (17 U.S.C. 909) are sufficient notices. Inclusion of a copyright/mask work notice
