The Conversion Extension fetches a list of exchange rates from Open Exchange Rates every 5 minutes. The Conversion Extension also stores a history of rates between currencies (for the recent past, it stores the rates for every 5 minutes. After 7 days it only stores one rate per hour per day).
When you activate the Conversion Extension, it automatically adds a list of global rates (updated every 5 mins) which allows the wallet apps to display the value of currencies in a user’s accounts in their chosen display currency e.g. showing what their EUR account balance is in USD. Whenever a value in the wallet apps is converted for display in a different currency, the wallet apps will always use a global rate for this calculation unless a custom rate overrides it.
Custom rate pairs
Custom rate pairs are comprised of a “from” and “to" currency and are defined in relation to a base currency, which in Rehive is always USD. Once the USD base rate is set, the Conversion Extension will use the base USD rate to work out all other rates between your custom rate currency and all other currencies.
You can override a global rate using a custom rate pair. With a custom rate pair, you can directly modify the rate or how the rate is calculated. If a custom rate pair exists, the wallet apps will use the rate value from the custom rate pair instead of the global rates for display. Custom rate pairs do not allow for currency exchange transactions - for that you need to set up Conversion Pairs.
Custom rate pairs can be used to define a rate between “from” and “to” currencies which are not included in the global rate pairs list e.g. between USD and a custom points currency. To set a custom rate for a custom points currency to be 1/100th the value of USD you would create a custom rate pair and set the rate to 0.01.
Read the full overview article to understand where rate pairs fit in to the Conversion Extension as a whole.