The structure of the text fields gives the user a clue about what kind of input is being
requested. For example, she can mentally map the six text fields in Figure 8-5 to the sixchunk
number written on her Photoshop CD case, and conclude that that’s the license
number she now needs to type in. Expectations are clear. She probably also realizes that
she doesn’t need to type in any spaces or hyphens to separate the six chunks.
This pattern usually gets implemented as a set of small text fields instead of one big one.
That alone can reduce data entry errors. It’s easier for someone to double-check several
short strings (two to five characters or so) than one long one, especially when numbers are
involved. Likewise, it’s easier to transcribe or memorize a long number when it’s broken
up into chunks. That’s how the human brain works.
Contrast this pattern to Forgiving Format, which takes the opposite tack: it allows you to
type in data in any format, without providing structural evidence of what’s being asked
for. (You can use other clues instead, like Input Hints.) Structured Format is better for very
predictable formats, Forgiving Format for open-ended input.