Plain-text reference tables for mechanical drawings. Every glyph and character name below is re-derived from the Unicode Character Database by tools/verify.py in this repository. CSV is the source of truth; this page is generated from it.
This is not a standard. The controlling document is the revision your drawing cites. Where these tables and a standard disagree, the standard is right.
ASME Y14.5-2009 carried 14 geometric characteristic symbols. The 2018 edition withdrew concentricity and symmetry, leaving 12. Both remain active in ISO 1101, so an ISO drawing may still carry either and is not out of date. Form controls never reference a datum; orientation, location and runout always do.
Six characteristics have a Unicode codepoint assigned to them by name. The rest borrow a geometry or arrow character. Borrowed glyphs are the usual reason a PDF shows a box instead of a symbol.
| Symbol | Characteristic | Category | Datum | Codepoint | Unicode name | Dedicated | ASME Y14.5-2018 | ISO 1101 |
|---|---|---|---|---|---|---|---|---|
| ⏤ | Straightness | form | no | U+23E4 | STRAIGHTNESS | yes | active | active |
| ⏥ | Flatness | form | no | U+23E5 | FLATNESS | yes | active | active |
| ○ | Circularity | form | no | U+25CB | WHITE CIRCLE | no | active | active |
| ⌭ | Cylindricity | form | no | U+232D | CYLINDRICITY | yes | active | active |
| ⌒ | Profile of a line | profile | optional | U+2312 | ARC | no | active | active |
| ⌓ | Profile of a surface | profile | optional | U+2313 | SEGMENT | no | active | active |
| ∠ | Angularity | orientation | yes | U+2220 | ANGLE | no | active | active |
| ⟂ | Perpendicularity | orientation | yes | U+27C2 | PERPENDICULAR | no | active | active |
| ∥ | Parallelism | orientation | yes | U+2225 | PARALLEL TO | no | active | active |
| ⌖ | Position | location | yes | U+2316 | POSITION INDICATOR | yes | active | active |
| ◎ | Concentricity | location | yes | U+25CE | BULLSEYE | no | withdrawn | active |
| ⌯ | Symmetry | location | yes | U+232F | SYMMETRY | yes | withdrawn | active |
| ↗ | Circular runout | runout | yes | U+2197 | NORTH EAST ARROW | no | active | active |
| ⌰ | Total runout | runout | yes | U+2330 | TOTAL RUNOUT | yes | active | active |
Circled-letter modifiers have no dedicated GD&T codepoint. RFS is listed because drawings still show it; under current ASME practice it applies by default and the symbol is not used.
| Symbol | Modifier | Meaning | Codepoint | Unicode name | Dedicated | Note |
|---|---|---|---|---|---|---|
| Ⓜ | MMC | maximum material condition | U+24C2 | CIRCLED LATIN CAPITAL LETTER M | no | |
| Ⓛ | LMC | least material condition | U+24C1 | CIRCLED LATIN CAPITAL LETTER L | no | |
| Ⓢ | RFS | regardless of feature size | U+24C8 | CIRCLED LATIN CAPITAL LETTER S | no | legacy - RFS applies by default and the symbol is no longer used in ASME practice |
| Ⓟ | Projected tolerance zone | projected tolerance zone | U+24C5 | CIRCLED LATIN CAPITAL LETTER P | no | |
| Ⓕ | Free state | free state | U+24BB | CIRCLED LATIN CAPITAL LETTER F | no | |
| Ⓣ | Tangent plane | tangent plane | U+24C9 | CIRCLED LATIN CAPITAL LETTER T | no | |
| Ⓤ | Unequally disposed | unequally disposed profile | U+24CA | CIRCLED LATIN CAPITAL LETTER U | no | |
| ⌀ | Diameter | diameter | U+2300 | DIAMETER SIGN | no | |
| ⌴ | Counterbore | counterbore or spotface | U+2334 | COUNTERBORE | yes | |
| ⌵ | Countersink | countersink | U+2335 | COUNTERSINK | yes | |
| ↧ | Depth | depth or deep | U+21A7 | DOWNWARDS ARROW FROM BAR | no | |
| ⌮ | All around | all around | U+232E | ALL AROUND-PROFILE | yes | |
| ⌱ | Dimension origin | dimension origin | U+2331 | DIMENSION ORIGIN | yes | |
| ⌲ | Conical taper | conical taper | U+2332 | CONICAL TAPER | yes | |
| ⌳ | Slope | slope | U+2333 | SLOPE | yes |
These are the preferred Ra numbers from ISO 1302, not a conversion table. N-grades are not used in ISO 21920-1:2021, which replaced ISO 1302 for new surface-texture specifications; they remain on drawings in circulation. There is no fixed Ra-to-Rz multiplier; this dataset does not print one.
| Grade | Ra (µm) | Ra (µin, conventional) |
|---|---|---|
| N1 | 0.025 | 1 |
| N2 | 0.05 | 2 |
| N3 | 0.1 | 4 |
| N4 | 0.2 | 8 |
| N5 | 0.4 | 16 |
| N6 | 0.8 | 32 |
| N7 | 1.6 | 63 |
| N8 | 3.2 | 125 |
| N9 | 6.3 | 250 |
| N10 | 12.5 | 500 |
| N11 | 25 | 1000 |
| N12 | 50 | 2000 |
git clone https://github.com/makenexa/engineering-reference-data.git
python tools/verify.pyThe verifier re-derives every codepoint from your local Unicode database, checks that concentricity and symmetry are withdrawn in ASME Y14.5-2018 and active in ISO 1101, and checks that the N-grade Ra series is the ISO 1302 preferred numbers (6.3 µm / 63 µin, not 6.4 / 64).
Human-readable drawing checklist that uses the same 14-row split: https://makenexa.com/resources/engineering-drawing-checklist/