| A | B |
|---|
| Aligned dimensioning | dimensions placed parallel to the dimensions line |
| Unidirectional dimensions | dimensions are placed horizontally so that they are read from the bottom of the drawing |
| Chain dimensioning | placing several dimensions in a straight line along an object to describe successive feature |
| Counterbore | similar to a spottface but the depth of the recess is larger |
| Countersink | chamfered recess at the end of a smaller hole used to receive the head of a fastener |
| Datum | an exact point axis, plane or surface from which features of a part are located |
| Dimensions | measurements of an object |
| Dual dimensioning | the first method devised to dimension engineering drawings with both inch and metric units |
| Feature control frame | rectangular compartment that contains a divided series of symbols identifying geometric tolerance |
| Geometric characteristic symbols | specify and explain form and positional tolerances |
| Geometric dimensioning and tolerancing | standard system devised to control interpretation of the form, profile orientation, location and run out of features of drawings |
| Leader | angular line used to point out special characteristics of objects |
| Location dimensions | indicate where particular details lie along or within in the objects |
| Notes | use to clarify information |
| Overall dimensions | provide the overall object size and tell the manufacturer how large a piece of material to use to make the objects |
| Size dimensions | specify how large the particular details are |
| Spotface | recess at the end of a smaller hole used to provide a bearing surface |
| Tolerance | an allowable variance from the original dimension |
