Geomentrical tolerance Symbols[

                      Geomentrical tolerance  Symbols[edit]

 

Tolerances: Type of tolerances used with symbols in feature control frames can be 1) equal bilateral 2) unequal bilateral 3) unilateral 4) no particular distribution (a "floating" zone)

Tolerances for the profile symbols are equal bilateral unless otherwise specified, and for the position symbol tolerances are always equal bilateral. For example, the position of a hole has a tolerance of .020 inches. This means the hole can move ±.010 inches, which is an equal bilateral tolerance. It does not mean the hole can move +.015/−.005 inches, which is an unequal bilateral tolerance. Unequal bilateral and unilateral tolerances for profile are specified by adding further information to clearly show this is what is required.

Geometric tolerancing reference chart (per ASME Y14.5 M-1982)
Type of control	Geometric characteristics	Symbol	Unicode character	Relevant feature		Virtual condition affected	References datum	Modified by		Affected by
				Surface	Of size			Ⓜ	Ⓢ	Bonus	Shift
Form	Straightness[3]		⏤ U+23E4	Yes	Yes	Of size[a]	No	Of size[a]	No[c]	Ⓜ[d]	No
Form	Flatness[4]		⏥ U+23E5	Yes	No	No	No	No	No[c]	No	No
Form	Circularity[4]		○ U+25CB	Yes	No	No	No	No	No[c]	No	No
Form	Cylindricity		⌭ U+232D	Yes	No	No	No	No	No[c]	No	No
Profile	Profile of a line		⌒ U+2312	Yes	No	No	Yes[e]	No	No[c]	No	Datum, Ⓜ[b]
Profile	Profile of a surface		⌓ U+2313	Yes	No	No	Yes[e]	No	No[c]	No	Datum, Ⓜ[b]
Orientation	Perpendicularity		⟂ U+27C2	Yes	Yes	Of size[a]	Yes	Of size[a]	No[c]	Ⓜ[d]	Datum, Ⓜ[b]
Orientation	Angularity		∠ U+2220	Yes	Yes	Of size[a]	Yes	Of size[a]	No[c]	Ⓜ[d]	Datum, Ⓜ[b]
Orientation	Parallelism		∥ U+2225	Yes	Yes	Of size[a]	Yes	Of size[a]	No[c]	Ⓜ[d]	Datum, Ⓜ[b]
Location	Symmetry[f][g]		⌯ U+232F	No	Yes	Yes	Yes	No	No	No	No
Location	Position		⌖ U+2316	No	Yes	Yes	Yes	Yes	Yes	Ⓜ[d]	Datum, Ⓜ[b]
Location	Concentricity[f]		◎ U+25CE	No	Yes	Yes	Yes	No	No[c]	No	No
Run-out	Circular run-out		↗ U+2197	Yes	Yes	Of size[a]	Yes	No	No[c]	No	No
Run-out	Total run-out		⌰ U+2330	Yes	Yes	Of size[a]	Yes	No	No[c]	No	No

1.       ^ Jump up to:^{a b c d e f g h i j} When applied to a feature of size.

2.       ^ Jump up to:^{a b c d e f g} When a datum feature of size is referenced with the maximum material condition modifier.

3.       ^ Jump up to:^{a b c d e f g h i j k l} Automatically^[b]

4.       ^ Jump up to:^{a b c d e} When an maximal material condition modifier is used.

5.       ^ Jump up to:^a b Can also be used as a form control without a datum reference.

6.       ^ Jump up to:^a b In the 2018 revision, both concentricity and symmetry were eliminated and are no longer supported.

7.       ^ The symmetry symbol's characteristics were not included in the version of the chart that this chart is derived from. The symmetry symbol was dropped from the Y14.5M standard around 1982 and re-added around 1994.

Symbols used in a "feature control frame" to specify a feature's description, tolerance, modifier and datum references
Symbol	Unicode character	Modifier	Notes
	Ⓕ U+24BB	Free state	Applies only when part is otherwise restrained
	Ⓛ U+24C1	Least material condition (LMC)	Useful to maintain minimum wall thickness
	Ⓜ U+24C2	Maximum material condition (MMC)	Provides bonus tolerance only for a feature of size
	Ⓟ U+24C5	Projected tolerance zone	Useful on threaded holes for long studs
	Ⓢ U+24C8	Regardless of feature size (RFS)	Not part of the 1994 version. See para. A5, bullet 3. Also para. D3. Also,
	Ⓣ U+24C9	Tangent plane	Useful for interfaces where form is not required
		Continuous feature	Identifies a group of features that should be treated geometrically as a single feature
		Statistical tolerance	Appears in the 1994 version of the standard, assumes appropriate statistical process control.
	Ⓤ U+24CA	Unequal bilateral	Added in the 2009 version of the standard, and refers to unequal profile distribution. Number after this symbol indicates tolerance in the "plus material" direction.