---
type: "gdt-symbol"
name: "Profile of a Surface"
symbol: "⌓"
unicode: "U+2313"
unicode_name: "SEGMENT"
category: "profile"
category_name: "Profile controls"
datum_required: "sometimes"
tolerance_zone: "Two surfaces offset from the true profile"
aliases: ["profile of a surface gdt", "surface profile"]
standard: "ASME Y14.5 (cited, not reproduced); ISO 1101"
verified: "August 1, 2026"
url: https://shopmath.org/gdt/profile-of-a-surface
---

# Profile of a Surface (⌓) — GD&T Symbol, Tolerance Zone and Datum Rules

The most general control in the system: a three-dimensional band around the theoretically exact surface that the actual surface must stay inside. Referenced to datums it locates and orients the surface as well as controlling its form, which is why it can stand in for flatness, position, and orientation on a single feature.

- **Symbol**: ⌓ (Unicode U+2313)
- **Category**: Profile controls
- **Tolerance zone**: Two surfaces offset from the true profile
- **Datum reference**: references a datum in some applications
- **Standard**: ASME Y14.5 (cited, not reproduced); ISO 1101

## Profile of a Surface at a Glance

| Property | Value |
| --- | --- |
| Characteristic | Profile of a Surface |
| Symbol | ⌓ |
| Unicode codepoint | U+2313 |
| Unicode name | SEGMENT |
| Category | Profile controls |
| Tolerance zone | Two surfaces offset from the true profile |
| Datum reference | references a datum in some applications |
| Standard | ASME Y14.5 (cited, not reproduced); ISO 1101 |

## How Profile of a Surface Behaves

Profile of a Surface belongs to the profile controls group. Control a surface or outline against its theoretically exact geometry.

## Other Profile controls Controls

The controls in the same category — the ones a drawing is choosing between when it specifies profile of a surface.

| Control | Symbol | Tolerance zone or effect | Datum |
| --- | --- | --- | --- |
| [Profile of a Line](https://shopmath.org/gdt/profile-of-a-line.md) | ⌒ | Two curves offset from the true profile, in each cross-section | references a datum in some applications |

## Sources and Method for Profile of a Surface

### Profile of a Surface definition

- **Source**: Symbols and codepoints: Unicode Character Database (Unicode License v3). Characteristic list cross-checked against NASA MSFC GD&T Basics (public domain). Descriptions written from scratch; no ASME Y14.5 text reproduced.
- **Method**: compiled
- **Verified against**: Unicode Character Database codepoint check; 98/98 structural checks passed

### Assumptions

- Descriptions are original prose. No ASME Y14.5 definitional text, worked example or figure is reproduced — the standard is cited, not copied.
- Symbol glyphs and codepoints are from the Unicode Character Database; a drawing may render the same characteristic with a different font.
- Dataset scope: EXCLUDED: all ASME Y14.5 definitional text, worked examples and figures. Every description on this site is original prose.

**Data last verified**: August 1, 2026

## Common Questions About Profile of a Surface in GD&T

### What does Profile of a Surface mean in GD&T?

The most general control in the system: a three-dimensional band around the theoretically exact surface that the actual surface must stay inside. Referenced to datums it locates and orients the surface as well as controlling its form, which is why it can stand in for flatness, position, and orientation on a single feature.

### What is the GD&T symbol for profile of a surface?

Profile of a Surface uses the ⌓ symbol — Unicode U+2313 (SEGMENT). It sits in the first compartment of the feature control frame.

### Does Profile of a Surface need a datum?

Profile of a Surface references a datum in some applications. Whether a datum appears depends on how the control is applied.

### What is the tolerance zone for Profile of a Surface in GD&T?

The profile of a surface tolerance zone is: Two surfaces offset from the true profile.

## Related pages

- Previous control: [Profile of a Line](https://shopmath.org/gdt/profile-of-a-line.md) (⌒)
- Next control: [Angularity](https://shopmath.org/gdt/angularity.md) (∠)
- All symbols: [GD&T symbol reference](https://shopmath.org/gdt.md)
- Tolerances: [ISO 286 fit reference](https://shopmath.org/fits.md)

---

*Source: [ShopMath](https://shopmath.org/gdt/profile-of-a-surface) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*