---
type: "gdt-symbol"
name: "Profile of a Line"
symbol: "⌒"
unicode: "U+2312"
unicode_name: "ARC"
category: "profile"
category_name: "Profile controls"
datum_required: "sometimes"
tolerance_zone: "Two curves offset from the true profile, in each cross-section"
aliases: ["profile of a line gdt", "line profile"]
standard: "ASME Y14.5 (cited, not reproduced); ISO 1101"
verified: "August 1, 2026"
url: https://shopmath.org/gdt/profile-of-a-line
---

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

Controls the shape of a cross-sectional outline against its theoretically exact geometry. The zone is two-dimensional and applies section by section, which makes it the right control for extrusions and swept shapes where each slice matters but the whole surface need not be held.

- **Symbol**: ⌒ (Unicode U+2312)
- **Category**: Profile controls
- **Tolerance zone**: Two curves offset from the true profile, in each cross-section
- **Datum reference**: references a datum in some applications
- **Standard**: ASME Y14.5 (cited, not reproduced); ISO 1101

## Profile of a Line at a Glance

| Property | Value |
| --- | --- |
| Characteristic | Profile of a Line |
| Symbol | ⌒ |
| Unicode codepoint | U+2312 |
| Unicode name | ARC |
| Category | Profile controls |
| Tolerance zone | Two curves offset from the true profile, in each cross-section |
| Datum reference | references a datum in some applications |
| Standard | ASME Y14.5 (cited, not reproduced); ISO 1101 |

## How Profile of a Line Behaves

Profile of a Line 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 line.

| Control | Symbol | Tolerance zone or effect | Datum |
| --- | --- | --- | --- |
| [Profile of a Surface](https://shopmath.org/gdt/profile-of-a-surface.md) | ⌓ | Two surfaces offset from the true profile | references a datum in some applications |

## Sources and Method for Profile of a Line

### Profile of a Line 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 Line in GD&T

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

Controls the shape of a cross-sectional outline against its theoretically exact geometry. The zone is two-dimensional and applies section by section, which makes it the right control for extrusions and swept shapes where each slice matters but the whole surface need not be held.

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

Profile of a Line uses the ⌒ symbol — Unicode U+2312 (ARC). It sits in the first compartment of the feature control frame.

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

Profile of a Line 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 Line in GD&T?

The profile of a line tolerance zone is: Two curves offset from the true profile, in each cross-section.

## Related pages

- Previous control: [Cylindricity](https://shopmath.org/gdt/cylindricity.md) (⌭)
- Next control: [Profile of a Surface](https://shopmath.org/gdt/profile-of-a-surface.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-line) — data verified August 1, 2026. Reference data; verify against the governing standard before manufacture.*