Advances are scientific, economic, social, or any other type of general accomplishment. They can enable the construction of particular types of units. They are, however, different than tech points and development.
Form: advance-type symbol properties...
This form defines a new type of advance, named by symbol. Naming details are similar to those for unit types.
GlobalVariable: a*
This variable evaluates to a list of all advance types, listed in the same order as they were defined.
GlobalVariable: non-advance
This variable has a value that is never an advance type.
AdvanceTypeProperty: rp n
This property is the number of research points necessary to achieve the
advance. Defaults to 1.
AdvanceTypeProperty: ai-next-goal list
A weighted list of possible advances to select as a research goal if the current advance is completed and was a research goal.
GlobalVariable: ai-initial-research-goals list
A weighted list of possible advances to select as a research goal if none is currently set.