The UCR-1 basket contains:
This means its value is roughly 0.65 USD, or 0.61 EUR, etc. It can be used as a unit of value when choosing a particular nation state's currency is undesirable. In that sense, transactions in UCR-1 are like conversations in Esperanto.
UCR-1 was defined on [date to be determined] and currencies represented in the basket are roughly rated by nominal GDP of the corresponding country. The weights for UCR-1, the first-generation unicurn, are now fixed and will never change. The value of one first-generation unicurn is expected to decrease over time due to probable inflation of the currencies it refers to.
There are currently no concrete plans to define more generations of unicurn (UCR-2, UCR-3, etc), but one option would be to define one new generation each year.