Glossary

What is yin? What is yang? Look no further.

This glossary sets out a list of words that refer to specific terminologies, constants, variables or functions in Opus.

Term	Definition
Yang	A collateral type, e.g. ETH, WBTC
Yin	The synthetic
Abbot	The module that acts as the point-of-entry for end-users to manage their troves.
Absorber	A stability pool where users may deposit yin and participate in liquidations, as well as to earn a percentage of debt surplus and additional reward tokens (if any).
Allocator	The module that provides a list of recipients of debt surplus, and their percentage allocations, to the Equalizer.
Base rate	The interest rate for a given yang
Caretaker	The module that is responsible for closing down the Shrine and the protocol in a graceful manner, ensuring that the remaining collateral assets are fairly distributed between both trove owners and yin holders.
Ceiling	This may refer to: 1. Shrine's debt ceiling: Maximum amount of debt allowed for the entire protocol 2. A Transmuter's debt ceiling: Maximum amount of debt that can be minted for a Transmuter module
Controller	The module that adjusts a global multiplier of interest rates for troves.
Deposit	Transferring the underlying collateral asset of a yang to the protocol for a trove
Enter	Transferring the underlying collateral asset of a yang from an address to its Gate
Epoch	A variable period of time tied to the shares used for internal accounting in the Absorber only.
Equalizer	The module that balances the Shrine's budget by either minting debt surpluses or allowing anyone to wipe out debt deficits. It also distributes minted debt surpluses to the recipients from the Allocator module.
Era	A variable period of time that spans multiple intervals during which the base rates of all yangs did not change.
Exit	Transferring the underlying collateral asset of a yang from its Gate to an address
Forge	Mint yin that is backed by a trove's value
Gate	Adapter for the underlying collateral tokens of yangs that holds the deposited amounts
Interval	A time step representing a fixed discrete block of time in the Shrine
LTV	Loan-to-value ratio
Melt	Pay down a trove's debt by burning yin
Provide	Depositing yin to the Absorber
Purger	The liquidation module
Ray	Fixed point number with 27 decimal precision
Remove	Withdrawing yin from the Absorber, if any remaining.
Seer	The oracle module that fetches prices from oracle adapters and submits yangs' prices to the Shrine.
Sentinel	A wrapper module over Gates.
Shrine	The core accounting module.
Threshold	The maximum amount of debt as a percentage of its total value. This may be in reference to a yang, a trove or the Shrine.
Trove	A collateralized debt position.
Wad	Fixed point number with 18 decimal precision.
Withdraw	Withdrawing the underlying collateral asset for a yang from the protocol for a trove

Disambiguating the different concepts of time

There are three distinct concepts of time that are used in the smart contracts for Opus: interval, era and epoch.

• Interval is a discrete time step of a fixed length of 30 minutes that underpins the Shrine, setting the frequency for price and multiplier updates.

• Era is a variable number of intervals where the base rates for yangs remain unchanged. Its sole purpose is to facilitate the calculation of the average base rates for yangs in the Shrine for a given span of intervals.

• Epoch is a variable period of time that is tied to the "shares" used for internal accounting in the Absorber only. It is used to calculate the amount of yin, absorbed assets and rewards that a provider to the Absorber is entitled to withdraw. An epoch is entirely independent of an interval or era.