Embedded format controls limit the reusability of programs. The problem is examined using a stream output example. It may be avoided if a map from data types to formatting options is passed to output service routines instead of a list of specific formats. Such a map is here called a “style”.This concept can be used with any programming language. However, it is most natural in the context of a language which offers data abstractions and user-defined generic operators. CONCISE is an experimental programming language in use to test the effectiveness of these technologies. CONCISE programs exploiting styles show how they help make program reusability feasible. As a byproduct, output formating becomes more flexible than it is with current approaches. © 1982, ACM. All rights reserved.