<Li> Avoid dimensioning the center line, except when it passes through the center hole . </Li> <Li> Avoid intersecting projection or dimension lines . </Li> <Li> If the space for dimensioning is insufficient, you may reverse arrow heads and replace adjacent arrow heads with dots . </Li> <P> Any engineering drawing requires specifications in terms of dimensions . Dimensions are classified as the following: </P>

The primary unit of measurement for engineering drawing and design in mechanical industries