Translations:TechDraw Geometric dimensioning and tolerancing/73/en

From FreeCAD Documentation
Symbols used in the 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, Figure 3-8.
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.