# ERTP Glossary

# AllegedName

Human-readable name of a kind of rights. The alleged name should not be trusted as an accurate depiction, since it is provided by the maker of the mint and could be deceptive, but is useful for debugging and double-checking.

The AllegedName must be a string.

# AmountMath

AmountMath executes the logic of how amounts are changed when digital assets are merged, separated, or otherwise manipulated. For example, a deposit of 2 bucks into a purse that already has 3 bucks gives a new balance of 5 bucks. An empty purse has 0 bucks. AmountMath relies heavily on polymorphic MathHelpers, which manipulate the unbranded portion.

# Amounts

Amounts are the canonical description of tradable goods. They are manipulated by issuers and mints, and represent the goods and currency carried by purses and payments. They can be used to represent things like currency, stock, and the abstract right to participate in a particular exchange.

An amount is composed of a Brand with an Extent.

# AssetHolder

Purses and Payments are AssetHolders.

# Brand

Identifies the kind of issuer.

# ERTP

Electronic Rights Transfer Protocol - Agoric's fungible and nonfungible token standard that uses object capabilities to enforce access control. Instead of having to prove ownership of a corresponding private key, in the world of object capabilities, if your program has a reference to an object, it can call methods on that object. If it doesn't have a reference, it can't. For more on object capabilities, see Chip Morningstar's post.

# Extent

Extents describe the extent of something that can be owned or shared: How much, how many, or description of unique asset. (Pixel(3,2), $3 or ‘Right to occupy on Tuesdays’). Fungible extents are normally represented by natural numbers. Other extents may be represented as strings naming a particular right, or an arbitrary object that sensibly represents the rights at issue.

Extent must be Comparable.

# Issuer

Can create empty purses and payments, but it cannot mint new amounts. The issuer can also transform payments (splitting payments, combining payments, burning payments, and claiming payments exclusively). The issuer should be gotten from a trusted source and then relied upon as the decider of whether an untrusted payment is valid.

# MathHelpers

Arithmetic on extents. MathHelpers are used by AmountMath to do their extent arithmetic, and then brand the result, making a new amount.

# Mint

The admin facet of the issuer, and the only object with the authority to mint new digital assets.

# Purse

An AssetHolder. Purses hold amounts of certain rights issued by Mints, specifically amounts that are stationary. Purses can transfer part of the balance they hold in a payment, which has a narrower interface.

See more: Purse API

# Payment

An AssetHolder. Payments hold amounts of certain rights issued by Mints, specifically amounts that are in transit. Amounts from payments can be deposited in purses, but otherwise, the entire amount is available when the payment is transferred. Payments can be converted to Purses.

See more: Payment API