Spot the cross (resembling the addition symbol) to find the center of every circle or partial circle. Circles include holes for example, while partial circles can be the rounded edges of a table.
Check next to countersunk holes' specifications for the V-like shape. "Countersunk" is the term used for holes with a conically shaped surface added to their opening. This symbol is depicted next to the hole's specifications on top views, while it is part of the design on sectioned front views.
Look for the upside-down "Π" symbol for counterbored holes. These are holes featuring a flat-bottomed cylindrical shape added to their opening. As with the countersink symbol, you can find it next to the hole's specifications on the top view.
Find the horizontal line with the arrow facing downwards to learn about a feature's depth. You can find it only on the specifications section of top views. An alternative to the depth symbol is its abbreviation, DP.
Search for arrows pointing towards circles. On the end of an arrow you can see a number along with an "O" with a line crossing through it. This signifies the circle's diameter.