Glossary
Angularity
 ASME The condition of a line element, surface, feature’s center plane, tangent plane, or feature’s axis at an implied or specified basic angle of any value from one or more datum planes or datum axes. Reference: ASME Y14.5-2018, par. 3.1
Angularity Tolerance
 ISO A geometrical tolerance that controls the orientation of the surface, median plane, or median line relative to one or more datums. Reference: ISO 1101:2012, Clause 18.11
Annotation
 ASME ISO Dimensions, tolerances, notes, text, or symbols visible without any manual or external manipulation. Dimension(s), tolerance(s), note(s), text or symbol(s) visible without any manual or external manipulation. Reference: ASME Y14.41-2012, par. 3.1 Reference: ISO 10209:2012, Clause 9.1
Annotation Element
 Common An entity in the CAD model that contains an annotation, such as a dimension or a geometric tolerance. Reference: None
Assembly Model
 ASME ISO A model in which the product described is an assembly of two or more items. A model in which the product described is an assembly of two or more items. Reference: ASME Y14.41, par. 3.3 Reference: ISO 10209:2012, Clause 9.3
Associated Feature
 ISO An ideal feature established from a non-ideal surface model or from a real feature through an association operation (can be established from a derived or an integral feature). Reference: ISO 17450-1:2011; Clause 3.3.8
Basic Dimension
 ASME A theoretically exact dimension. Reference: ASME Y14.5-2009, par. 1.3.23
Bonus Tolerance
 ASME Where MMC or LMC is specified for a geometric tolerance, an increase in the tolerance equal to the departure of the feature of size from the specified material condition. Reference: ASME Y14.5-2009, par. 2.8.2 and 2.8.4
 ISO The selected parts of a computer-aided design (CAD) model as presented on screen or paper. Reference: ISO 10209:2012, Clause 11.23 (from ISO 13567-1:1998)
 Common An element that defines some aspect of the geometry of a CAD model, such as an extruded cut or a hole. Note that this differs from feature as defined in ASME Y14.5 or geometrical feature as defined in ISO 17450. Reference: None
 Common A common-language term used interchangeably with the term Model. ‘CAD’ is an abbreviation for Computer-Aided Design. Reference: None
Circular Runout Tolerance
 ASME ISO A geometric tolerance that provides control of circular elements of a surface. The tolerance is applied independently at each circular measuring position as the part is rotated the full angular extent of the surface about the simulated datum axis. A geometrical tolerance that specifies that the extracted line... • in any cross-section plane perpendicular to a datum axis shall be contained between two planar concentric circles with a difference in radii that is equal to the indicated tolerance value • in any cylindrical cross-section whose axis is coincident to a datum axis shall be contained between equally sized two circles separated by a distance equal to the indicated tolerance value Reference: ASME Y14.5-2009, par. 9.4.1 Reference: ISO 1101:2012, Clause 18.15
Circularity (Roundness)
 ASME The condition of a surface where, • for a feature other than a sphere, all points of the surface intersected by a plane perpendicular to an axis or spine (curved line) are equidistant from that axis or spine • for a sphere, all points of the surface intersected by any plane passing through a common center are equidistant from that center Reference: ASME Y14.5-2009, par. 5.4.3
Coaxiality Tolerance
 ISO A geometrical tolerance that controls a median line of a feature to be within a cylindrical tolerance zone, centered on a datum axis. Reference: ISO 1101:2012, Clause 18.13.2
Collective Requirement
 ISO Where MMR or LMR is indicated, the combination of two independent requirements (e.g., diameter tolerance and position tolerance) into a single requirement that more accurately simulates the intended function of the workpiece. Reference: ISO 2692:2006
Common Datum
 ASME ISO A datum established from two or more datum features considered simultaneously. A datum established from two or more datum features considered simultaneously. Reference: None Reference: ISO 5459:2011, Clause 3.9
Common Zone (CZ)
 ISO A modifying symbol that follows the tolerance in the tolerance frame and indicates that a single tolerance zone is applied to several separate features. Reference: ISO 1101:2012, Clause 8.5
Concentricity
 ASME The condition where the median points of all diametrically opposed elements of a surface of revolution (or median points of correspondingly located elements of two or more radially disposed features) are congruent with a datum axis (or center point). Reference: ASME Y14.5-2009, fig. 1-37
Concentricity Tolerance
 ISO A geometrical tolerance that controls the center point of a feature at any cross-section to be within a circular tolerance zone, centered on a datum axis. Reference: ISO 1101:2012, Clause 18.13.1
Counterbore
 ASME ISO A cylindrical flat-bottomed hole that enlarges another coaxial hole that is typically used when a fastener is required to sit flush with or below the level of a workpiece's surface. A cylindrical flat-bottomed hole that enlarges another coaxial hole that is typically used when a fastener is required to sit flush with or below the level of a workpiece's surface. Reference: ASME Y14.5-2009, fig. 1-37 Reference: None
Cylindricity
 ASME The condition of a surface of revolution in which all points of the surface are equidistant from a common axis. Reference: ASME Y14.5-2009, par. 5.4.4
Cylindricity Tolerance
 ISO A geometrical tolerance that specifies that the extracted cylindrical surface shall be contained between two coaxial cylinders with a difference in radii that is equal to the indicated tolerance value. Reference: ISO 1101:2012, Clause 18.4
Datum
 ASME ISO A theoretically exact point, line, plane, or combination thereof derived from the theoretical datum feature simulator. One or more situation features of one or more features associated with one or more real integral features selected to define the location or orientation, or both, of a tolerance zone or an ideal feature representing for instance a virtual condition. Reference: ASME Y14.5-2009, par. 1.3.13 Reference: ISO 5459:2011, Clause 3.4
Datum Axis
 ASME ISO The axis of a datum feature simulator established from the datum feature. A datum that is a theoretically exact straight line. Reference: ASME Y14.5-2009, par. 1.3.14 Reference: ISO 5459:2011, Clause 3.4
Datum Feature
 ASME ISO A feature that is identified with either a datum feature symbol or a datum target symbol. A real (not ideal) integral feature used for establishing a datum Reference: ASME Y14.5-2009, par. 1.3.16 Reference: ISO 5459:2011, Clause 3.2
Datum Feature Displacement
 ISO The allowable movement or looseness between the part datum feature and the simulated datum feature. Reference: None
Datum Feature Shift
 ASME The allowable shift/displacement of a datum feature from the boundary established by the datum feature simulator. Reference: ASME Y14.5-2009, par. 4.11.9
Datum Feature Simulator
 ASME There are two types datum feature simulators: • Theoretical: The theoretically perfect boundary used to establish a datum from a specified datum feature. • Physical: The physical boundary used to establish a simulated datum from a specified datum feature. Reference: ASME Y14.5-2009, par. 1.3.17
Datum Plane
 ASME ISO The plane of a datum feature simulator established from the datum feature A datum that is a theoretically exact plane. Reference: None Reference: ISO 5459:2011, Clause 3.4
Datum Reference Frame (DRF)
 ASME ISO A set of three mutually perpendicular planes that constitutes a reference frame for dimensioning and tolerancing. This is an ASME term that is similar to the ISO term Datum System. The ASME term is used throughout the GD&T Advisor application and documentation, but refers to a datum system when in the context of ISO GPS. See Datum System. Reference: ASME Y14.5-2009, par. 4.7 Reference: ISO 5459:2011, Clause 3.10
Datum System
 ISO A set of two or more situation features established in a specific order from two or more datum features. Reference: ISO 5459:2011, Clause 3.10
Datum Target
 ASME ISO The designated points, lines, or areas that are used in establishing a datum. A portion of a datum feature which can nominally be a point, a line segment, or an area. Reference: ASME Y14.5-2018, par. 3.21 Reference: ISO 5459:2011, Clause 3.11
Degrees of Freedom (DOF)
 Common A translational or rotational movement of a part relative to the axes of a coordinate system. All parts have six degrees of freedom, three translational and three rotational. Reference: None
Degrees of Variance (DOV)
 Common The constrainable degrees of freedom of a feature, based on symmetry. Reference: None
Design Model
 ASME ISO The portion of the data set that contains model geometry and supplemental geometry. The portion of the data set that contains model and supplemental geometry. Reference: ASME Y14.41-2012, par. 3.12 Reference: ISO 10209:2012, Clause 9.8
Dimension
 ASME ISO A numerical value or mathematical expression in appropriate units of measure used to define form, size, orientation, or location of a part or feature. The distance between two features or the size of a feature of size. Reference: ASME Y14.5-2009, par. 1.3.22 Reference: ISO 10209:2012, Clause 4.6 (from ISO 129-1:2004)
Draft
 ASME A taper given to a part so that it can be withdrawn from a model or die. Reference: ASME Y14.8-2009, par. 1.8.5
Draft Angle
 ISO Angle added to a geometrical feature of a pattern or mold to ensure the easy removal of the pattern or molded part from the mold or to improve the quality of the product. Reference: ISO 8062-1:2007
Drawing
 ASME ISO An engineering document or digital data file that discloses (either directly or by reference) by means of graphic or textual presentations, or by combinations of both, the physical or function requirements of an item. See CAD Drawing Reference: ASME Y14.100-2004, par. 3
Driven Dimension
 Common A dimension that is derived from the 3D model and cannot be directly modified. Reference: None
Driving Dimension
 Common A dimension that, when modified, causes a change to the CAD geometry. Reference: None
Envelope Requirement
 ISO For a feature of size, the envelope of perfect form at maximum material condition may not be violated. Reference: None
Extracted Feature
 ISO A geometrical feature defining a set of a finite number of points (applies to an integral or to a derived feature). Reference: ISO 17450-1:2011; Clause 3.3.7
Feature
 ASME ISO A physical portion of a part (such as a surface, pin outside diameter, hole, or slot) or its representation on drawings, models, or digital data files. Reference: ASME Y14.5-2018, par. 3.31
Feature Control Frame
 ASME A rectangle divided into compartments containing the geometric characteristic symbols followed by the tolerance value or description, modifiers, and any applicable datum feature references. Reference: ASME Y14.5-2009, par. 3.4.1
Feature Extents
 Common The boundaries of a feature. Reference: None
Feature of Size
 ASME ISO One cylindrical or spherical surface, a circular element, or a set of two opposed parallel elements or opposed parallel surfaces, each of which is associated directly with a toleranced dimension. A geometrical shape defined by a linear or angular dimension which is a size. Reference: ASME Y14.5-2009, par. 1.3.32.1 Reference: ISO 10209:2012, Clause 4.7 (from ISO 129-1:2004)
Fixed Fastener Assembly
 ASME An assembly of two (or more) components that are held together with restrained fasteners, such as screws in tapped holes or studs. Reference: ASME Y14.5-2009, par. B.4
Flatness
 ASME The condition of a surface or derived median plane having all elements in one plane. Reference: ASME Y14.5-2009, par. 5.4.2
Flatness Tolerance
 ASME ISO A geometric tolerance that specifies a tolerance zone defined by two parallel planes within which the surface or derived median plane must lie. A geometrical tolerance that specifies that the extracted (actual) surface of a feature shall be contained between two parallel planes that are separated by the indicated tolerance value. Reference: ASME Y14.5-2009, par. 5.4.2 Reference: ISO 1101:2012, Clause 18.2
Form
 Common The shape of a feature. Reference: None
Form Tolerance
 ASME ISO A geometric tolerance that controls the form (such as straightness, flatness, circularity and cylindricity) of a feature. A geometrical tolerance that controls only form deviations of the feature. Reference: ASME Y14.5-2009, par. 5.2 Reference: ISO 1101:2012; Clause 15
Free State
 ASME The condition in which no externally introduced forces other than gravity are applied to a part. Reference: ASME Y14.5-2018, par. 3.38
Free State Condition
 ISO The condition of a part subjected only to the forces of gravity. Reference: ISO 10579:2010
General Tolerance
 ASME ISO A tolerance, usually located in the notes section of a data set, that applies to multiple features of the part. A tolerance that applies where an individual tolerance indication is not specified. Reference: ASME Y14.100-2004, par. 4.26.6 Reference: ISO 2768-1,2:1989
Geometrical Characteristic Symbol
 ASME ISO The symbolic means of indicating geometric characteristics; used to specify the type of control for a geometric tolerance. A symbol representing a geometrical characteristic. Reference: ASME Y14.5-2009, par. 3.3.1 Reference: ISO 1101:2012
Geometric Dimensioning and Tolerancing (GD&T)
 Common A system for defining and communicating engineering tolerances. It uses a symbolic language on engineering drawings and CAD models that explicitly describes nominal geometry and its allowable variation. Reference: None
Geometrical Feature
 ISO A point, line, surface, volume or a set of these items. Reference: ISO 17450-1:2011; Clause 3.3
Geometrical Product Specifications (GPS)
 ISO A symbolic language for communicating workpiece requirements on engineering drawings and CAD models. Reference: None
Geometric Tolerance
 ASME The general term applied to the category of tolerances used to control size, form, profile, orientation, location, and runout. Reference: ASME Y14.5-2009, par. 1.3.62
Geometrical Tolerance
 ISO The general term applied to the category of tolerances used to control size, form, profile, orientation, location, and run-out. Reference: None
Independency Principle
 ISO The general term applied to the category of tolerances used to control size, form, profile, orientation, location, and run-out. Reference: None
Integral Feature
 ISO A geometrical feature belonging to the real surface of the workpiece or to a surface of the model. Reference: ISO 17450-1:2011; Clause 3.3.5
ISO Fit System
 ISO A system of fits comprising of shafts and holes tolerance by the ISO code system for tolerances on linear sizes. Reference: ISO 286-1:210, Clause 3.4.1
Least Material Boundary (LMB)
 ISO The limit defined by a tolerance or combination of tolerances that exists on or inside the material of a feature. Reference: ASME Y14.5-2009, 1.3.3
Least Material Condition (LMC)
 ASME ISO The condition in which a feature of size contains the least amount of material within the stated limits of size (e.g., maximum hole diameter, minimum shaft diameter). The state of the considered extracted feature, where the feature of size is at that limit of size where the material of the feature is at its minimum everywhere, e.g. maximum hole diameter and minimum shaft diameter. Reference: ASME Y14.5-2009, par. 1.3.38 Reference: ISO 2692, Clause 3.6
Least Material Requirement (LMR)
 ISO A requirement for a feature of size, defining a geometrical feature of the same type and of perfect form, with a given value for the intrinsic characteristic (dimension) equal to LMVS, which limits the non-ideal feature on the inside of the material. Reference: ISO 2692, Clause 3.13
Least Material Size
 ISO The dimension defining the least material condition of a feature. Reference: ISO 2692, Clause 3.7
Least Material Virtual Size (LMVS)
 ISO The size generated by the collective effect of the least material size, LMS, of a feature of size and the geometrical tolerance given for the derived feature of the same feature of size. Reference: ISO 2692, Clause 3.10
Limits of Size
 ASME The specified maximum and minimum sizes. Reference: ASME Y14.5-2009, par. 1.3.55
Line Profile Tolerance
 ISO A geometrical tolerance that specifies that in each section, the extracted profile shall be contained between two equidistant lines enveloping circles of a diameter equal to the indicated tolerance, the centers of which are situated on a line having the theoretically exact geometrical form. Reference: ISO 1101:2017, Clause 17.5
Location Tolerance
 ASME A geometric tolerance that controls location of a feature relative to another feature or to a datum reference frame. Reference: ASME Y14.5-2009, par. 7.1
Material Boundary Modifier
 ASME A symbol that indicates the material boundary at which a datum feature is to be simulated. Reference: None
Material Condition
 ASME Refers the size of the feature relative to its limits of size (e.g., RFS, MMC, or LMC). Reference: None
Material Condition Modifier
 ASME ISO A symbol that indicates the material condition (e.g., RFS, MMC, or LMC) at which the specified tolerance value applies. See Maximum Material Requirement, MMR, and Least Material Requirement, LMR. Reference: None Reference: None
Maximum Material Boundary (MMB)
 ASME The limit defined by a tolerance or combination of tolerances that exists on or outside the material of a feature. Reference: ASME Y14.5-2009, par. 1.3.4
Maximum Material Condition (MMC)
 ASME ISO The condition in which a feature of size contains the maximum amount of material within the stated limits of size (e.g., minimum hole diameter, maximum shaft diameter). The state of the considered extracted feature, where the feature of size is at that limit of size where the material of the feature is at its maximum everywhere, e.g. minimum hole diameter and maximum shaft diameter. Reference: ASME Y14.5-2009, par. 1.3.39 Reference: ISO 2692, Clause 3.4
Maximum Material Requirement (MMR)
 ISO A requirement for a feature of size, defining a geometrical feature of the same type and of perfect form, with a given value for the intrinsic characteristic (dimension) equal to MMVS, which limits the non-ideal feature on the inside of the material. Reference: ISO 2692, Clause 3.12
Maximum Material Size
 ISO The dimension defining the maximum material condition of a feature. Reference: ISO 2692, Clause 3.5
Maximum Material Virtual Size (MMVS)
 ISO The size generated by the collective effect of the maximum material size, MMS, of a feature of size and the geometrical tolerance given for the derived feature of the same feature of size. Reference: ISO 2692, Clause 3.10
Model
 ASME ISO A combination of design model, annotation, and attributes that describes a product. A combination of design model, annotations, and attributes that describes a product. Reference: ASME Y14.41-2012, par. 3.21 Reference 10209:2012, Clause 9.16.1 (from ISO 16792:2006)
Multi-surface feature
 Common A feature that consists of multiple surfaces. Reference: None
Nominal Value
 Common The stated value of a dimension. Reference: None
Not Convex (NC)
 ISO A modifying symbol that appears near the tolerance frame and indicates that only concave deviations from flat are permissible. Reference: ISO 1101:2012, Clause 6.3
Non-rigid Part
 ASME ISO A part that has some flexibility and for which some dimensions and tolerances apply under a specified restraint (as indicated by a note). A part which deforms to an extent that in the free state is beyond the specified dimensional and/or geometrical tolerances. Reference: None Reference: ISO 10579:2010
Order of Precedence
 Common The sequence in which datum features are referenced in a feature control frame (e.g., primary, secondary, tertiary). Reference: None
Orientation Tolerance
 ASME ISO A geometric tolerance that controls angular relationships. A geometrical tolerance that controls orientation and form deviations of the feature. Reference: ASME Y14.5-2009, par. 6.2 Reference: ISO 1101:2012; Clause 15
Parallelism
 ASME The condition of a surface or a feature’s center plane, equidistant at all points from a datum plane; or a feature’s axis, equidistant along its length from one or more datum planes or datum axes. Reference: ASME Y14.5-2009, par. 6.3.1
Parallelism Tolerance
 ISO A geometrical tolerance that specifies that the extracted (actual) surface, line, median line or median plane shall be contained between two parallel planes separated by the indicated tolerance value which are parallel to a datum axis or datum plane. Reference: ISO 1101:2012, Clause 18.9
Parameter
 Common A variable in the CAD system. Reference: None
Parametric Dimension
 Common A dimension that defines the size, orientation, or location of a CAD feature. Reference: None
Part
 ASME One item, or two or more items joint together, that is not normally subject to disassembly without destruction or impairment of designed use. Reference: ASME Y14.100-2004, par. 3
Part Model
 ISO A model in which the product described is a single item. Reference: ISO 10209:2012 (from ISO 29845:2011)
Pattern
 ASME ISO Two or more features or features of size to which a locational geometric tolerance is applied and are grouped by one of the following methods: nX, n COAXIAL HOLES, ALL OVER, A↔B, n SURFACES, simultaneous requirements, or INDICATED. Two or more features or features of size to which a locational geometric tolerance is applied and are grouped by a notation such as nx. Reference: ASME Y14.5-2009, par. 1.3.42 Reference: None
Perpendicularity
 ASME The condition of a surface, a feature’s center plane, or a feature’s axis at a right angle to a datum plane or datum axis. Reference: ASME Y14.5-2009, par. 6.3.1
Perpendicularity Tolerance
 ISO A geometrical tolerance that specifies that the extracted feature shall be contained between two parallel planes separated by the indicated tolerance value which are perpendicular to a datum axis or datum plane. Reference: ISO 1101:2012, Clause 18.10
Position Tolerance
 ASME ISO A geometric tolerance that defines a zone within which the center, axis, or center plane of a feature of size is permitted to vary from a true (theoretically exact) position or, where specified on an MMC or LMC basis, a boundary located at the true position, that may not be violated by the surface or surfaces of the considered feature of size. A geometrical tolerance that specifies that the extracted center point, median line, median plane, or surface of a feature shall be contained within the specified zone from the theoretically exact location. Reference: ASME Y14.5-2009, par. 7.2 Reference: ISO 1101:2012, Clause 18.12
Predominant Datum Reference Frame (DRF)
 Common The main datum reference frame for the model. It usually orients and locates the model in the assembly. Reference: None
Profile
 ASME The outline of a surface, a shape made up of one or more features, or a two-dimensional element of one or more features. Reference: ASME Y14.5-2009, par. 8.2
Profile Any Line Tolerance
 ISO A geometrical tolerance that specifies that in each section, the extracted profile shall be contained between two equidistant lines enveloping circles of a diameter equal to the indicated tolerance, the centers of which are situated on a line having the theoretically exact geometrical form. Reference: ISO 1101:2012, Clause 18.5
Profile Any Surface Tolerance
 ISO A geometrical tolerance that specifies that the extracted surface shall be contained between two equidistant enveloping spheres of a diameter equal to the indicated tolerance, the centers of which are situated on a surface having the theoretically exact geometrical form. Reference: ISO 1101:2012, Clause 18.7
Profile of a Line Tolerance
 ASME A geometric tolerance that defines a two-dimensional tolerance zone at each line element of the feature relative to the true profile. Reference: ASME Y14.5-2009, par. 8.2.1.2
Profile of a Surface Tolerance
 ASME A geometric tolerance that defines a three-dimensional tolerance zone extending along the length and width (or circumference) of the feature relative to the true profile. Reference: ASME Y14.5-2009, par. 8.2.1.1
Profile Tolerance
 ASME ISO A geometric tolerance used to control form or a combinations of size, form, orientation and location of a feature relative to a true profile. A geometric tolerance used to control form or a combinations of size, form, orientation and location of a feature relative to a line or a surface having the theoretically exact geometrical form. Reference: ASME Y14.5-2009, par. 8.2 Reference: None
Projected Tolerance Zone
 ASME ISO A tolerance zone that is projected above the design model surface. A tolerance zone placed outside the extent of the toleranced feature. Reference: ASME Y14.5-2009, par. 7.4.1 Reference: ISO 1101:2012; Clause 13
Reciprocity Requirement (RPR)
 ISO An additional requirement for a feature of size used as an addition to the maximum material requirement, MMR, or the least material requirement, LMR, to indicate that the size tolerance is increased by the difference between the geometrical tolerance and the actual geometrical deviation. Reference: ISO 2692:2006, Clause 3.14
Regardless of Material Boundary (RMB)
 ISO Indicates that a datum feature simulator progresses from MMB toward LMB until it makes maximum contact with the extremities of a feature. Reference: ASME Y14.5-2009, par. 1.3.49
Regardless of Feature Size (RFS)
 ASME ISO Indicates that a geometric tolerance applies at any increment of size of the actual mating envelope of the feature of size. A condition where the size dimension and geometrical tolerances for a feature of size apply independently. Reference: ASME Y14.5-2009, par. 1.3.48 Reference: None
Restraint
 ASME ISO The application of force(s) to a part to simulate its assembly or functional condition resulting in possible distortion of the part from its free-state condition. A force applied to a workpiece during measurement, which may result in geometrical distortion. Reference: ASME Y14.5-2009, par. 1.3.50 Reference: ISO 10579:2010
Roundness Tolerance
 ISO A geometrical tolerance that specifies that the extracted circumferential line, in any cross-section, shall be contained between two coplanar concentric circles with a difference in radii that is equal to the indicated tolerance value. Reference: ISO 1101:2012, Clause 18.3
Rule #1
 ASME The form of an individual regular feature of size is controlled by its limits of size. Reference: ASME Y14.5-2009, par. 2.7.1
Rule #2
 ASME RFS applies, with respect to the individual tolerance, and RMB applies, with respect to the individual datum feature reference, where no modifying symbol is specified. Reference: ASME Y14.5-2009, par. 2.8
Runout Tolerance
 ASME A tolerance used to control the functional relationship of one or more features to a datum axis established from a datum feature specified at RMB. Reference: ASME Y14.5-2009, par. 9.2
Separate Requirement
 ASME A geometric tolerance that is not considered to be part of a simultaneous requirement set. Reference: ASME Y14.5-2009, par. 4.19
Simultaneous Requirement
 ASME Where two or more geometric tolerances apply as a single pattern or part requirement. A simultaneous requirement applies to position or profile tolerances that reference identical datum reference frames. Reference: ASME Y14.5-2009, par. 4.19
Situation Feature
 ISO A point, straight line, plane or helix from which the location and orientation of features, or both, can be defined. Reference: ISO 17450-1:2011; Clause 3.3.1.1.3
Size Dimension
 ASME ISO A dimension between two opposed surfaces, line elements, or points belonging to a feature of size. A dimension between two opposed surfaces, line elements, or points belonging to a feature of size. Reference: None Reference: None
Statistical Tolerancing
 ASME The assigning of tolerances to related components of an assembly based on sound statistics (such as the assembly tolerance is equal to the square root of the sum of the squares of the individual tolerances). Reference: ASME Y14.5-2009, par. 2.17
Straightness
 ASME The condition where an element of a surface, or a derived median line, is a straight line. Reference: ASME Y14.5-2009, par. 5.4.1
Straightness Tolerance
 ISO A geometrical tolerance that specifies that … • any extracted line shall be contained between two parallel straight lines separated by the indicated tolerance value • the extracted median line of a cylindrical surface shall be contained within a cylindrical zone with a diameter equal to the indicated tolerance value
Sub-feature
 Common A feature that represents a portion of a multi-surface feature. Reference: None
Surface Profile Tolerance
 ISO A geometrical tolerance that specifies that the extracted surface shall be contained between two equidistant enveloping spheres of a diameter equal to the indicated tolerance, the centers of which are situated on a surface having the theoretically exact geometrical form. Reference: ISO 1101:2017, Clause 17.7
Symmetry
 ASME The condition where the median points of all opposed or correspondingly located elements of two or more feature surfaces are congruent with a datum axis or center plane. Reference: ASME Y14.5-2009, par. 7.7.2
Symmetry Tolerance
 ISO A geometrical tolerance that specifies that the extracted median surface shall be constrained between two parallel planes separated by the indicated tolerance value, which are symmetrically disposed about a datum plane. Reference: ISO 1101:2012, Clause 18.14
Tangent Plane Modifier
 ASME A symbol that indicates that a geometric tolerance applies only to the tangent plane of the tolerance surface. Reference: ASME Y14.5-2009, par. 6.5
Theoretically Exact Dimensions (TED)
 ISO Dimensions that indicate the theoretically exact location, orientation, or profile. Reference: ISO 1101:2012, Clause 11
Tolerance
 ASME ISO The total amount a specified dimension is permitted to vary. The tolerance is the difference between the maximum and minimum limits. The total amount a specified dimension is permitted to vary. Reference: ASME Y14.5-2009, par. 1.3.60 Reference: None
Tolerance Analysis
 Common A calculation to determine the effect of the accumulation of tolerances on product requirements. Reference: None
Tolerance Frame
 ISO A rectangular frame divided into two or more compartments that contain a geometrical characteristic symbol, a tolerance value with optional modifiers, and datum indications, if needed. Reference: ISO 1101:2012
Tolerance Zone
 Common The area or volume that represents the total amount that a feature is permitted to vary from the specified dimensions. Reference: None
Total Runout Tolerance
 ASME ISO A geometric tolerance that provides control of all surface elements. The tolerance is applied simultaneously to all circular and profile measuring position as the part is rotated about the datum axis. A geometrical tolerance that specifies that the extracted surface shall be contained between … • two coaxial cylinders with a difference in radii that is equal to the indicated tolerance value and whose axes are coincident with a datum axis. • two parallel planes that are separated by a distance equal to the indicated tolerance value and which are perpendicular to a datum axis. Reference: ASME Y14.5-2009, par. 9.4.2 Reference: ISO 1101:2012, Clause 18.16
Translation Modifier
 ASME A symbol, ▷, following a datum feature reference in the feature control frame indicates that the basic location of the datum feature simulator is unlocked and the datum feature simulator is able to translate within the specified geometric tolerance to fully engage the feature. Reference: ASME 15.5, par 4.11.10
Unequally Disposed Profile Symbol
 ASME A symbol that indicates a unilateral or unequally disposed profile tolerance. Reference: ASME Y14.5-2009, par. 3.3.22
Workpiece
 ISO A physical (real) part. Reference: None