>> The help says it gives the sum of the Ascending, Leading and Descending.
>>
>> What the hell are those exactly...I figured it -was- the height of the
>> largest glyph in the font.
>>
The term "leading" originally referred to the thickness of the divider 
(made of lead) placed between rows of type when setting type by hand. 
(Yes, I've done this.) In most computer applications it has been 
redefined as the distance from one baseline to the next, which is what 
you are looking for.

Apps like Quark XPress usually let you specify a default leading as a 
proportion of the font size. If it's set to add 10%, then a line of 10-pt 
type would be positioned 11 pts below the previous line, and 15-pt type 
would be placed at 16.5 pts below the last.

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