Originally Posted by JS
How do you print a three dimensional barcode on a two dimensional surface? Is it three dimensional invisible ink that appears two dimensional to me?
Terms are somewhat misleading. The barcodes printed on UA boarding passes are actually *two* dimensional, meaning that they have little "blocks" of data that vary in both the up/down and side/side dimensions. If you want to compare this to a "one" dimensional barcode, think of a UPC code on a cereal box -- note that it's just a set of lines that run in a single dimension.
Why these one- and two-dimensional barcodes are all of a sudden called "two-" and "three-" dimensional escapes me... ;-)
--lj