Brief Description of the Drawings: 7 Proven Rules

Every patent specification with figures needs a short block of text that names them. It is easy to treat the brief description of the drawings as boilerplate — one-line captions dashed off after the real drafting is done. That habit generates avoidable office actions. The section is a rule-bound part of the specification under 37 CFR 1.74, and it is one of the first things an examiner compares against the sheets themselves. When the text and the drawings disagree, the examiner does not quietly pick the better one. You get an objection, and fixing it under the new-matter bar is harder than getting it right the first time.

What the Brief Description of the Drawings Must Contain

The governing rule is short. 37 CFR 1.74, titled Reference to drawings, provides: “When there are drawings, there shall be a brief description of the several views of the drawings and the detailed description of the invention shall refer to the different views by specifying the numbers of the figures and to the different parts by use of reference letters or numerals (preferably the latter).”

Two obligations sit inside that one sentence, and they are often confused. The first is the standalone section — a description of the several views. The second is a running obligation on the detailed description to refer to figures by number and to parts by reference numeral. Satisfying one does not satisfy the other. A specification that discusses “the valve assembly” at length without ever writing “FIG. 3” has a 1.74 problem even if its figure list is immaculate.

Placement is also prescribed. Under 37 CFR 1.77(b), the preferred arrangement of the specification lists the “Brief description of the several views of the drawing” as item (9), sitting after the summary and before the detailed description. The USPTO treats 1.77 as a preferred order rather than an absolute one, but there is no advantage in deviating, and examiners searching for the section expect it there.

What the rule does not require is equally worth knowing. There is no minimum length, no mandated verb, and no requirement that the section explain how the invention works. Its job is identification, not exposition.

Rule 1: Describe Every View, and Only the Views That Exist

The most common defect is arithmetic. The drawings contain nine figures; the brief description lists eight. Or the description lists FIG. 7 while the sheets stop at FIG. 6 because a view was dropped late in drafting and the text was never revisited.

Both directions draw an objection. An undescribed figure violates the requirement to describe the several views. A described figure that does not exist is worse, because it suggests disclosure the application does not actually contain. Before filing, count the figures on the sheets and count the entries in the section. They must match exactly, with no gaps in the numbering.

This check costs a minute and it is the single highest-yield review step on the whole section. If you routinely file applications with more than a dozen figures, make it a docketed item rather than a habit.

Rule 2: The Single-View Trap in 37 CFR 1.84(u)

37 CFR 1.84(u)(1) governs how views are numbered: “The different views must be numbered in consecutive Arabic numerals, starting with 1, independent of the numbering of the sheets and, if possible, in the order in which they appear on the drawing sheet(s).” View numbers are preceded by the abbreviation “FIG.”

Then comes the exception that catches experienced drafters: “Where only a single view is used in an application to illustrate the claimed invention, it must not be numbered and the abbreviation ‘FIG.’ must not appear.”

This is a prohibition, not a preference. A single-figure application — common for provisionals, simple mechanical devices and many design filings — should not say “FIG. 1 is a perspective view of the device.” It should say “The drawing is a perspective view of the device.” Automated drafting templates almost always get this wrong, because they generate the figure label from a loop that starts at 1 regardless of how many views exist.

The consequence is minor in isolation — a drawing objection, correctable by amendment — but it is entirely avoidable, and it signals to the examiner that the drawings were not reviewed.

Rule 3: Name the View Type Accurately

37 CFR 1.84(h) contemplates plan, elevation, section and perspective views, along with detail views at a larger scale. The brief description should state which one each figure is, because the label carries technical meaning that the examiner relies on.

Calling a cutaway a “perspective view” is not a harmless simplification. A sectional view invokes the hatching conventions of 37 CFR 1.84(h)(3), and it usually needs a cutting-plane line on a companion figure. If the text says the figure is a section, the examiner will look for those features. If the text says perspective and the sheet plainly shows hatched cut surfaces, the mismatch invites scrutiny of the drawings as a whole.

Precision here is cheap. Our breakdown of patent drawing views covers when each type is appropriate and what each one obliges you to show.

• Plan view — looking directly down at the subject.
• Elevation view — a straight-on side, front or rear view.
• Sectional view — a cut through the subject, hatched, with a cutting plane indicated elsewhere.
• Perspective view — a three-dimensional representation.
• Exploded view — components separated along an axis to show assembly relationships.
• Detail view — an enlarged portion of another figure, at a stated larger scale.

Rule 4: Keep the Text Neutral About Scope

The brief description of the drawings is prose in the specification, and prose in the specification can be read against you during claim construction. Drafters who write “FIG. 2 is a sectional view of the invention” have handed an opponent a sentence equating the invention with one illustrated arrangement.

The safer convention, now near-universal in careful US practice, is to describe figures as embodiments rather than as the invention: “FIG. 2 is a sectional view of a valve assembly according to one embodiment.” It costs three words and removes an argument.

The same caution applies to functional characterisations. A figure list is not the place to assert that a component “prevents leakage” or “improves efficiency.” Save the advantages for the detailed description, where they can be properly supported, and keep this section to identification.

Rule 5: Reference Numerals Belong to the Detailed Description

37 CFR 1.74 puts the reference-numeral obligation on the detailed description, not on the figure list. The brief description identifies views; the detailed description identifies parts. Loading the figure list with every numeral in the application makes it unreadable without satisfying anything the rule asks for.

A numeral used in the drawings but never mentioned in the specification is a classic drawing objection, and so is a numeral that appears in the text but on no sheet. Consistency across the three surfaces — figures, figure list and detailed description — is what examiners actually check. Our guide to patent drawing reference numerals sets out a numbering scheme that survives amendment.

One practical exception: where a figure is defined by a particular part, naming that part with its numeral in the figure list can aid clarity, as in “FIG. 4 is a detail view of the sealing collar 42 of FIG. 3.” Used sparingly, that is helpful. Used throughout, it is noise.

Rule 6: Design Applications Follow 37 CFR 1.152

Design practice changes the calculus, because in a design application the drawings are the claim. 37 CFR 1.152 requires that the drawings comply with 37 CFR 1.84 and “contain a sufficient number of views to constitute a complete disclosure of the appearance of the design.”

1.152 also sets the conventions the figure list has to describe honestly. Appropriate and adequate surface shading should be used to show the character or contour of the surfaces represented, and solid black surface shading is not permitted except to represent the colour black or colour contrast. Broken lines may be used to show visible environmental structure, but may not be used to show hidden planes and surfaces that cannot be seen through opaque materials. Alternate positions of a design component shown by full and broken lines in the same view are not permitted.

Because broken lines subtract from the claimed design, the statement explaining them is doing legal work. It belongs in the specification alongside the figure list, and it must match the sheets exactly — if the text disclaims a portion as unclaimed environment, that portion has to actually be drawn in broken lines. We cover the mechanics in design patent broken lines.

Design figure lists are also conventionally exhaustive: front, rear, left side, right side, top and bottom elevations plus a perspective view, with an explicit statement where a view is omitted as a mirror image or as flat and unornamented.

Rule 7: In Europe, Cite Rule 42(1)(d) EPC — Not Rule 46

The European Patent Convention imposes the same duty in fewer words. Rule 42(1) EPC, on the content of the description, requires the applicant to “briefly describe the figures in the drawings, if any” at subparagraph (d). That is the provision to cite for the European equivalent of this section.

The formatting rule that used to sit beside it is gone. Rule 46 EPC, headed Form of the drawings, was deleted — along with Rule 49(3) to (12) EPC — by decision CA/D 10/22, which the Administrative Council adopted at its 172nd session on 13 October 2022 and which entered into force on 1 February 2023. The detailed presentation requirements were moved out of the Implementing Regulations and into a decision of the President of the EPO, so that they can be revised as the EPO’s digital filing processes evolve. Rule 49 EPC still carries the general provisions governing the presentation of application documents.

This matters for anyone maintaining precedent files or drafting checklists. A great deal of published guidance — including material still circulating on firm websites — cites Rule 46 EPC as live authority for European drawing standards. It has not been in force since February 2023. For substantive guidance the current sources are the EPO Guidelines for Examination at Part A, Chapter IX, and the President’s decision, not Rule 46.

Practical consequence: a European figure list should still describe each figure, but do not lift a “Rule 46 EPC compliant” assurance from an old template into a new filing or a client letter.

Keeping the Section Correct After the Drawings Change

Most defects in the brief description of the drawings are not drafting errors at all. They are synchronisation errors introduced when the drawings change and the text does not.

Adding a figure during prosecution means amending the specification to describe it. That amendment is subject to the prohibition on new matter under 35 U.S.C. 132(a), so the new view has to be supported by the application as filed — a new figure that adds detail nowhere present in the original disclosure will not survive, no matter how carefully the figure list is worded. Renumbering is the other hazard: inserting a view between FIG. 3 and FIG. 4 forces every downstream numeral, every figure-list entry and every cross-reference in the detailed description to move together.

Our walkthrough of amending patent drawings covers replacement-sheet practice and the annotated-sheet requirement. The rule of thumb is simple: the figure list is amended in the same response as the sheets, never in a later one.

The same discipline applies when a continuation or divisional inherits a parent’s drawings but drops some of them. Copying the parent’s figure list wholesale into a child application that no longer contains all those figures is one of the more common ways this section goes wrong, and it is entirely mechanical to prevent.

A Pre-Filing Checklist

Run these checks before the application goes out. They take a few minutes and they intercept nearly every objection this section attracts.

1. The count of figures on the sheets equals the count of entries in the figure list, with no gaps in numbering.
2. If there is exactly one view, it is unnumbered and the abbreviation “FIG.” appears nowhere, per 37 CFR 1.84(u)(1).
3. Each entry names the correct view type, and sectional views have a cutting plane indicated on a companion figure.
4. Figures are described as embodiments, not as “the invention.”
5. Every reference numeral on a sheet appears somewhere in the detailed description, and vice versa.
6. For designs, the broken-line statement matches what is actually drawn in broken lines, per 37 CFR 1.152.
7. For European filings, the checklist cites Rule 42(1)(d) EPC and the EPO Guidelines A-IX — not the deleted Rule 46 EPC.

For the underlying sheet-level standards that the figures themselves must meet — margins, line weight, lettering and shading — see our detailed treatment of 37 CFR 1.84 drawing requirements and the objections examiners raise most often in patent drawing mistakes. The authoritative text of the rules is published by the USPTO in the Manual of Patent Examining Procedure, and the European provisions are on the EPO’s legal texts site.

Get the Figures and the Figure List Right Together

PerspireIP’s illustrators prepare USPTO, EPO and PCT-compliant sheets and deliver a matching figure list drafted to 37 CFR 1.74, so the text and the drawings arrive consistent rather than being reconciled after an office action. See our patent drawing services, or talk to us about a pending filing.

Frequently Asked Questions