①,Edge of head may be rounded or flat. ②,Screws of these lengths and shorter shall have undercut heads. ③,● Type AB thread-forming , see table [Table 40] ◆ Type A thread-forming, see table [Table 42] ▲ Type B and BP thread forming, see table [Table 41]; Type BF and BT thread cutting, see table [Table 43] ■ Type C thread forming, see table [Table VI-1]; Type D, F, G and T thread cutting, see table [Table 44]; and Type TRS thread-rolling ,see table [Table 45] |