Actions are applied to notes or containers (including map adornments) and are the effect part of an agent. The parent (with the action) acts on its children. A special form of Action called a Rule can be used to act just on the note/agent itself.
Values - of attributes - are changed and information is gathered or changed as a result; the value of (system) read-only attributes may not be altered by action code. Any resulting effects are applied only to the children. Rules are actions that only affect the note itself.
Agents may have actions.
Actions and rules may use simple arithmetic and logical expressions. A broad range of functions can be run at action/rule scope often removing the need to use export codes. See Actions & Rules.
The article linked below describes now-deprecated usage, as export codes should not be used routinely for internal operations; ^version^ and ^docTitle^ are the only things can only be accessed internally via an export code.