Legends

Suitable descriptive legends may be used, or may be required by the examiner, where necessary for understanding of the drawing, subject to approval by the USPTO. They should contain as few words as possible.

Numbers, Letters, and Reference Characters

The English alphabet must be used for letters, except where another alphabet is customarily used, such as the Greek alphabet to indicate angles, wavelengths, and mathematical formulas.

Reference characters (numerals are preferred), sheet numbers, and view numbers must be plain and legible, and must not be used in association with brackets or inverted commas, or enclosed within outlines (encircled). They must be oriented in the same direction as the view so as to avoid having to rotate the sheet. Reference characters should be arranged to follow the profile of the object depicted.

Numbers, letters, and reference characters must measure at least 0.32 cm. (1/8 inch) in height. They should not be placed in the drawing so as to interfere with its comprehension. Therefore, they should not cross or mingle with the lines. They should not be placed upon hatched or shaded surfaces. When necessary, such as indicating a surface or cross section, a reference character may be underlined and a blank space may be left in the hatching or shading where the character occurs so that it appears distinct.

The same part of an invention appearing in more than one view of the drawing must always be designated by the same reference character, and the same reference character must never be used to designate different parts.

Reference characters not mentioned in the description shall not appear in the drawings. Reference characters mentioned in the description must appear in the drawings.

Lead Lines and Arrows

Lead lines are those lines between the reference characters and the details to which they refer. Such lines may be straight or curved and should be as short as possible. They must originate in the immediate proximity of the reference character and extend to the feature indicated. Lead lines must not cross each other. Lead lines are required for each reference character except for those which indicate the surface or cross section on which they are placed. Such a reference character must be underlined to make it clear that a lead line has not been left out by mistake. Lead lines must be executed in the same way as lines in the drawing.

Arrows may be used at the ends of lines, provided that their meaning is clear, as follows:

• on a lead line, a freestanding arrow to indicate the entire section toward which it points;
• on a lead line, an arrow touching a line to indicate the surface shown by the line looking along the direction of the arrow; or
• to show the direction of movement.

Copyright or Mask Work Notice

A copyright or mask work notice may appear in the drawing, but must be placed within the sight of the drawing immediately below the figure representing the copyright or mask work material and be limited to letters having a print size of 0.32 cm. to 0.64 cm. (1/8 to 1/4 inches) high. The content of the notice must be limited to only those elements provided for by law. For example, "©1983 John Doe" (17 U.S.C. 401) and "MJohn Doe" (17 U.S.C. 909) would be properly limited and, under current statutes, legally sufficient notices of copyright and mask work, respectively. Inclusion of a copyright or mask work notice will be permitted only if the authorization language set forth in 37 CFR sect.1.71(e) is included at the beginning (preferably as the first paragraph) of the specification.

Numbering of Sheets of Drawings and Views

The sheets of drawings should be numbered in consecutive Arabic numerals, starting with 1, within the sight (the usable surface). These numbers, if present, must be placed in the middle of the top of the sheet, but not in the margin. The numbers can be placed on the right-hand side if the drawing extends too close to the middle of the top edge of the usable surface. The drawing sheet numbering must be clear and larger than the numbers used as reference characters to avoid confusion. The number of each sheet should be shown by two Arabic numerals placed on either side of an oblique line, with the first being the sheet number and the second being the total number of sheets of drawings, with no other marking.

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). Partial views intended to form one complete view, on one or several sheets, must be identified by the same number followed by a capital letter. View numbers must be preceded by the abbreviation "FIG". 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.

Numbers and letters identifying the views must be simple and clear and must not be used in association with brackets, circles, or inverted commas. The view numbers must be larger than the numbers used for reference characters.

Security Markings

Authorized security markings may be placed on the drawings provided they are outside the sight, preferably centered in the top margin.

Corrections

Any corrections on drawings submitted to the USPTO must be durable and permanent.

Holes

No holes should be made by the applicant in the drawing sheets. Rather than use of a staple, a non-hole producing binder clip should be used.

Patent and Trademark Depository Library (PTDL) Program

The Patent and Trademark Depository Library Program is comprised of a network of Patent and Trademark Depository Libraries (PTDLs) located in the 50 states, the District of Columbia, and Puerto Rico which provide access to many of the same products and services offered at the USPTO search facilities in Alexandria, VA. The scope of PTDL collections, hours of operation, services, and fees (where applicable) vary depending on PTDL location. Users are advised to call ahead to determine products and services available at a particular PTDL. PTDLs also offer automated access to patent and trademark information. All PTDLs offer free access to the Cassis CD-ROM series search tools to assist patrons in the use of patent and trademark collections.