What ⌯ means
It limits how far the middle may stray from a reference.
Imagine a slot that should be centered in a block. Its opposite walls can have small manufacturing variations. A symmetry tolerance checks whether the midpoints between those walls stay within a permitted zone centered on a datum plane—an ideal plane used as a reference for measurement.
The symbol identifies the type of requirement. The number beside it gives the tolerance, or allowed variation; the referenced datum establishes where the zone sits. These appear together in a divided rectangular box called a feature-control frame. The sign alone does not tell you how much variation is allowed.
Technical drawing notation for design, manufacturing and inspection.
⌯ and the position symbol specify different requirements; do not simply swap them.
Part of the collection
Don't confuse it with
1
Questions people ask
1Is symmetry still used in ASME Y14.5-2018?
No. That edition removed the symmetry control. You can still meet it on older drawings. Position is a possible alternative, but choosing a replacement requires reviewing the design requirement, not merely changing the symbol.
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How to type or find ⌯
- Search it as
- symmetry symbol · symmetry tolerance · GD&T symmetry
- Shows up in
- Anything that takes text · its shape is whatever your font draws
⌯\232FCodes and encoding1 code points
A visible symbol can contain several code points. JS .length counts UTF-16 units; UTF-8 counts bytes.