The advance measure is the total space the glyph takes, either horizontally or vertically, depending on the current writing direction. It is equal to the distance traveled by the cursor, placed directly in front of, and then shifted behind, the character.
This term is used in the definition of a number of CSS
The advance measure of unit
ch is either width or height of character "0" in the given typeface, depending on whether horizontal or vertical axis is currently used. A similarly advance measure of unit
ic is width or height of character "水".