Abstract
We investigate binary words and languages having a balanced structure of (scattered) subwords. We introduce a "difference function" D for binary words. For D=0, the resulting language is properly context-sensitive. Parikh matrices constitute a useful technical tool in the study, we investigate also the independence of their entries. The investigation is extended to concern ω-words and periodicity. For the Fibonacci word, the D-values are in many ways connected with the Fibonacci numbers.