The store statement lets you store a string of characters or keys in a buffer which can then be referenced with any and index. Proper use of store can reduce many keyboards down to a few rules. A store is terminated at the end of the line (or continuation lines). Stores can contain either Unicode or ANSI characters, but a single store cannot contain both. Stores can also contain virtual keys and deadkeys, and outs() statements.
The return statement was introduced in Keyman 3.0. Starting in version 6.0, deadkeys and virtual keys are allowed within stores. Version 5.0 and earlier did not allow these.