Availability of Data in Rules
Note to developers: See also the Developer Docs page on Data types for using hook_rules_data_info().
Data Objects
Rules extends Entity API and provides uniform access to Drupal's data types and instances.
Field of a referenced, referenced entity - worked example
Having read the comments on the link from the Rules UI (the parent to this page), I thought I'd take a moment to document what's taken me
Lists
Lists are collections of data objects that can be operated over in a loop. Any group of data items can be treated as a list, for example
Operations
Rules has many features for calculations, conversions, & transformations with support for complex logic on several data types. This can be
Selection
By default, Rules includes a direct input and a data selection interface.