Creo Elements/Direct Modeling GD&T
GLOSSARY
The symbolic means of indicating that a tolerance applies to surfaces all around the part. Place a circle at the junction in the leader that goes from the feature control frame to the part.
The symbolic means of indicating that a tolerance applies to a limited segment of a surface between designated extremities. Place a letter designating a point on the part on each side of the between symbol. The part points are designated with a letter and a leader line.
A theoretically exact point, axis, or plane derived from the true geometric counterpart of which the location or geometric characteristics of features of a part are established.
The symbolic means of indicating a datum feature consists of a capital letter enclosed in a square frame and a leader line extending from the frame and a leader line extending from the frame to the concerned feature, terminating with a triangle. The triangle may be filled or not filled. Letters of the alphabet (except I, O, and Q) are used as datum identifying letters. Where the same datum feature symbol is repeated to identify the same feature in other locations of the drawing, it need not be identified as reference.
The symbolic means of indicating a datum target is a circle divided horizontally into halves. The lower half contains a letter identifying the associated datum, followed by the target number assigned sequentially starting with 1 for each datum. A radial line attached to the symbol is directed to a target point, target line, or target area, as applicable. Where the datum target is an area, the area size is entered in the upper half of the symbol; otherwise, the upper half is left blank.
The datum target specifies a point, line, or area on a part used to establish a datum.
See Datum Target, point is specified by the above symbol.
See Datum Target,
See Datum Target,
A surface of adequatly precise form (such as a surface plate, a gage surface, or a mandrel) contacting the datum feature(s) and used to establish the simulated datum(s).
A point, axis, or plane established by processing or inspection equipment, such as the following simulators: a surface plate, a gage surface, or a mandrel.
Diametrical Feature
or Tolerance Zone 
This symbol is used to indecate diameter and precedes the value of the dimension or tolerance given. The symbol and the value are not separated by a space.
The general term applied to a physical portion of a part, such as a surface, pin, tab, hole, or slot.
A geometric tolerance for an individual feature is specified by means of a feature control frame divided into compartments containing the geometric characteristic symbol followed by the tolerance. Where applicable, the tolerance is preceded by the diameter symbol and followed by a material condition symbol.z
One cylindrical or spherical surface, or a set of two opposed elements or opposed parallel surfaces, associated with a size dimension.
Free state variation is the amount a part distorts after removal of external forces applied during manufacture, for instance, parts consisting essentially of shells or tubes with a thin wall thickness in proportion to the diameter. Geometric tolerances (e.g. circularity, cylindricitry, and concentricity) cannot be properly applied without specifying the amount of free-state variation on parts of this type.
Variations in the free state can occur in two ways: (1) distortion of a part due to its weight or flexibility (i.e. a non-rigid part), or (2) distortion due to internal stresses set up in fabrication (e.g. any pre-loading operations).
The total movement of an indicator where appropriately applied to a surface to measure its variations.
Least Material Condition
(LMC) 
The condition in which a feature of size contains the least amount of material within the stated limits of size - for example, maximum hole diameter, minimum shaft diameter. The use of this symbol in local and general notes is prohibited.
Unless otherwise specified, the limits of size of a feature prescribe the extent within which variations of geometric form, as well as size, are allowed. This control applies solely to individual features of size.
Maximum Material Condition
(MMC) 
The condition in which a feature of size contains the maximum amount of material within the stated limits of size - for example, minimum hole diameter, maximum shaft diameter. The use of this symbol in local and general notes is prohibited.
Regardless of Feature Size (RFS)
The term used to indicate that a geometric tolerance or datum reference applies at any increment of size of the feature within its size tolerance.
The term used to indicate that the form of a feature of size is perfect in flatness, straightness, roundness, and cylindricity when produced at the maximum material condition or MMC.
When it is desired to project a stated tolerance zone beyond the boundaries of a part the projected tolerance zone symbol is used. The symbol is placed after the stated tolerance and any modifiers and is followed by a value for the projection distance. The use of this symbol in local and general notes is prohibited.
When it is desired to control a planer surface with a plane defined by contacting the high points on the surface use the tangent plane symbol(ASME Y14.5 - Fig. 6-43). The symbol is placed in the feature control frame following the stated tolerance.
This tolerance type is apploed to single (individual) features or elements of single features; therfore form tolerances are not related to datums. This tolerance type includes straightness, flatness, circularity, and cylindricity.
A profile is the outline of an object in a given plane (two dimensional) that is derived from a cross section or projection from a part. The elements of a profile are straight lines, arcs, and other curved lines. With profile tolerancing, the true profile may be defined by basic radii, basic angular dimensions, basic coordinate dimensions, basic size dimensions, undimensioned drawings, or formulas. Profile tolerances include profile of a surface and profile of a line.
Angularity, parallelism, perpendicularity, and in some instances, profile are orientation tolerances applicable to related features. These tolerances control the orientation of features to one another. All orientation tolerances are defined in relation to datum features.
This tolerance type includes position, concentricity, and symmetry used to control the following relationships:
Runout is a composite tolerance used to control the functional relationship of one or more features of a part to a datum axis. There are two types of runout control, circular runout and total runout. The type used is dependent upon design requirements and manufacturing considerations. Circular runout is normally a less complex requirement than total runout.
