Besides cursor placement and state definition, the minimenus involved with rule definitions sometimes have additional options. When the rule is very long, tabs and margin seeking options are convenient.
In situations where incremental definition is convenient, markers are useful to distinguish between transitions that have been fixed and those which are still under consideration.
Another, although related, use for markers is to protect the marked states from the random number generator, so that the consequences of varying only a portion of a rule can be studied.