Section marker
Marks where the drawing is cut through to show a section. The arrow shows the way the section looks; the circle gives the section's number and the sheet it's drawn on.
This explains what a symbol represents on a drawing. Conventions vary between firms and standards, and a drawing's own legend takes precedence.
How to read it
In the A/E/C Graphics Standard the circle is split in two: the top half identifies the section and the bottom half gives the sheet it is on, and section sheets carry a 3 in the sheet-type position. The Army's print-reading manual describes the cutting plane as short heavy lines with arrowheads showing the viewing direction, with letters such as AA at the arrowheads. The Navy's blueprint reading course says the arrows point the way to look at the section.
Also searched as: building section symbol, section callout, section cut.
Look-alikes
An elevation marker and a detail callout use the same split circle. The sheet number tells them apart: 2 for elevations, 3 for sections, 5 for details.
More blueprint symbols
Sources
- A/E/C Graphics Standard, Release 2.2, ERDC/ITL SR-23-1, U.S. Army Engineer Research and Development Center, CAD/BIM Technology Center, secs. 4.2.4.1, 4.2.4.3
- Construction Print Reading in the Field, TM 5-704 / AFM 85-27, Departments of the Army and the Air Force, para. 1-3j
- Blueprint Reading and Sketching, NAVEDTRA 14040A, Naval Education and Training Command, U.S. Navy, ch. 2, viewing or cutting plane lines
Last reviewed September 24, 2026 by Rory Hansen. How we research