Apple LaserWriter 12/640 PS - Manual (Page 357)

TrueType fonts
A TrueType font is scalable, describing a typeface without rigidly specifying a
size. So it looks good whatever size you choose. TrueType fonts provide sharp
text at any size on screen or on paper. You can mix and match TrueType fonts
from various font vendors.
TrueType fonts store individual text characters as mathematical descriptions
of lines and curves, rather than as groups of pixels (a bitmap). When a
program asks for a character in a particular size, such as 33 points, the Mac
OS uses mathematical calculations to enlarge the character’s outline
to 33 points and fill in the dots for the monitor or printer output.
Sometimes you’ll still get jagged edges when you print a document, even
when you use a TrueType font. In nearly all cases, this is because there isn’t
enough memory available to scale the font properly for printing.
Because you don’t need a separate font for each character size in order for
your printing to look good (as you do with bitmapped fonts), TrueType font
names don’t have numbers in them.
332 Appendix C