As you've probably figured out by now, there is no one named "DC Lettering," at least not at DC. It turns out that DC Lettering is just what they call their computer lettering system. According to Wikipedia:
Most Marvel and DC books are now lettered using a graphics program such as Adobe Illustrator or Adobe Photoshop, and a font that resembles hand lettering. Computer lettering provides a lot of technical shortcuts, especially by combining the lettering work directly with digital art files, eliminating the tedious physical paste-up stage altogether.That's kind of sad that comics have switched to digital, but at the time, it is kind of archaic to have people drawing letters. That's progress.
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