A command can be:
It is composed of a single Interactive command. The simple commands are listed at the end of the document (see chapter 11 page §).
A mixed command is a list of simple commands separated by &. The various commands from the list will be applied successively. when we use the rr command (see chapter 4.43 page §) and we have just entered a mixed command, this mixed command will be entirely replayed.
Example of a mixed command: