A family of Microsoft word processing software products for creating web, email, and print documents.
AutoTextList fields are a great convenience for avoiding legacy form fields in older versions of Word, but in Word 2010 it might make more sense to use content controls. But there is no limit to the length of an AutoText entry; you just want the name of the entry to be short (just long enough to be distinguished from other entries by a knowledgeable user).
Content controls appear to work the same way, with a "display name" and "value," but it doesn't appear to me that the "value" is what is inserted when you select the display name; both fields are limited to 256 characters, so you're probably still better off with an AutoTextList field.