user18584: Sir/ Ma'am,
.
How to read the dimension labels of this IC?

user2881: Values above the horizontal lines are in inches. Values below it are in mm.

user4143: I have annotated your drawing a little to help you understand it better:


18584: <p>Sir/ Ma'am,
.
How to read the dimension labels of this IC?<a href="https://i.stack.imgur.com/36PTZ.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/36PTZ.jpg" alt="enter image description here"></a></p>
 2881: <p>Values above the horizontal lines are in inches. Values below it are in mm.</p>
 4143: <p>I have annotated your drawing a little to help you understand it better:
<a href="https://i.stack.imgur.com/hMxQV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/hMxQV.png" alt="enter image description here"></a></p>
