1. Position Tolerancing—Expanded Principles, Symmetry, and Concentricity9
Position Tolerancing—Expanded Principles, Symmetry, and Concentricity

2. Specify and explain composite position tolerance specifications.
Explain functional gaging methods for checking hole position tolerances specified at MMC.
Specify and explain composite position tolerance specifications.
Explain the effect of using identical datum feature references in multiple position tolerance specifications.
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3. Specify position tolerances for in-line holes.
Specify separate pattern requirements for groups of features not acting as a single pattern.
Specify position tolerances for in-line holes.
Specify tolerances to control symmetry.
Control coaxial features with position or concentricity tolerances, depending on the given application.
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4. Symmetry Position tolerance Symmetry tolerance
Symbol removed from standard in 1982
Symbol reinstated in 1994
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5. Position for Symmetry of Hole Patterns
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6. Symmetry for Features of Size
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7. Concentricity
Requires derived median line located relative to datum axis
Always has diameter symbol
Always applied RFS
Must have datum feature reference
Datum reference is always RMB
Rarely used
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8. Concentricity Feature Control Frame
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9. Concentricity Median Line
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10. Concentricity Zero Error
Even though a feature has surface and size variation, it may have no concentricity variation
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11. Composite Position Tolerance
One position symbol
Two or more segments
Same datums, same order, same modifiers
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12. PLTZF Pattern-locating tolerance zone framework Pronounced plotz
First segment
Located relative to datum reference frame
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13. FRTZF Feature-relating tolerance zone framework Pronounced fritz
Lower segment(s)
Not located relative to datum reference frame
Constrained in rotation relative to referenced datums
Must, at a minimum, overlap PLTZF
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14. Composite Position Application
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15. No Repeated Datum References
Free to float relative to datum reference frame
Features must be able to meet tolerance requirements in first and second segments
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16. Repeated Primary Datum Reference
Rotational degrees of freedom constrained relative to primary datum
Features must be able to meet tolerance requirements in first and second segments
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17. Repeated Primary and Secondary Datum Reference
Rotational degrees of freedom constrained relative to primary and secondary datum
Features must be able to meet tolerance requirements in first and second segments
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18. Functional Gaging for Position Tolerances at MMC
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19. Gaging a Composite Position Tolerance
Similar to single segment position tolerance
Two gages typically required to check composite tolerances
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20. Actual mating envelope
A true geometric counterpart of the feature that is at the maximum size that will fit within the hole or other internal feature or at the minimum size that will encompass a shaft or other external feature.
Concentricity
The allowable position tolerance controlling the derived median line relative to the datum axis. 
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21. Feature-relating tolerance zone framework (FRTZF)
The relative true positions of the features in a pattern.
Pattern-locating tolerance zone framework (PLTZF)
The true positions of the controlled features relative to the referenced datums.
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22. Simultaneous requirement
Tolerances shown in the feature control frame that contain identical datum feature references.
Symmetry
A condition where features on each side of a centerline or center plane are equal.
Unrelated actual mating envelope
A mating envelope that is not related to any datums and that encompasses all size and form variations on the feature.
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