Aperture
The white space at the end of an open counterIn typography, a counter is the area of a letter that is entirely or partly enclosed by a letter ... in typographyTypography is the art and technique of arranging letters to make written language legible, readable ....
In optics, an apertureThe white space at the end of an open counter in typography. In optics, an aperture is a hole or an ... is a hole or an opening through which light travels.