The content in a .b4x file consists of a series of vocab items (words or phrases) in a foreign language paired with their meanings in the native language of the intended learner. The items may also have sound associated with the foreign and/or native terms, as well as pictures. When you download a lesson as a .b4x file, it will have all the vocab items from that lesson.
The .b4x files can be run in several older programs from Transparent Language{{#rr5}}, including Rapid Rote{{/rr5}}.