What does CH HD in technical drawing?

In technical drawing, "CH" typically stands for "Center Hole," indicating a hole that is located at the center of a feature, such as a circle or an object. The "HD" often refers to "Hole Diameter," specifying the diameter measurement of that hole. Together, "CH HD" conveys essential information about the location and size of a center hole in the design. This notation helps ensure accurate fabrication and assembly of parts in engineering and manufacturing.