1. Geometric Dimensioning and Tolerancing
Chapter 2, Symbols and Abbreviations

2. Introduction GDT is a language of symbols
We will see an overview of the symbols associated with:
Dimensioning Symbols
Geometric Characteristics
Modifying Symbols

3. Dimensioning Symbols

4. Dimensioning Symbols
Diameter 
Radius R

5. Dimensioning Symbols
Spherical Diameter S
Spherical Radius SR

6. Dimensioning Symbols Controlled Radius Tolerance CR Number of Places 
A controlled radius has no ‘reversals’, but is a smooth curve within the tolerance zone.

7. Dimensioning Symbols
Counterbore/Spotface
Countersink

8. Dimensioning Symbols
Depth/Deep
Dimensions Not to Scale

9. Dimensioning Symbols
Conical taper
Slope

10. Dimensioning Symbols
Square
Reference Dimension

11. Dimensioning Symbols
Dimension Origin
Arc Length

12. Dimensioning Symbols
All Around
All Over

13. Dimensioning Symbols Chain Line
Used to identify a limited region to be treated differently from the rest of the part.

14. Geometric Characteristics
Explained in detail in Chapters 6 and 8.

15. Modifying Symbols

16. Modifying Symbols Maximum Material Condition MMC MMC
Refers to the size of the feature associated with the most material.

17. Modifying Symbols Least Material Condition LMC LMC
Refers to the size of the feature associated with the least material.

18. Modifying Symbols Continuous Feature Basic Dimension
Used to describe a theoretically exact size.

19. Modifying Symbols
Between

20. Evaluation