Currency Formats

Xahau has two kinds of digital asset: XAH and tokens. Both types have high precision, although their formats are different.

Comparison

The following table summarizes some of the differences between XAH and tokens in Xahau:

XAH	Tokens
Has no issuer.	Always issued by a Xahau account.
Specified as a string.	Specified as an object.
Tracked in accounts.	Tracked in trust lines.
Can never be created; can only be destroyed.	Can be issued or redeemed freely.
Minimum value: 0. (Cannot be negative.)	Minimum value: -9999999999999999e80. Minimum nonzero absolute value: 1000000000000000e-96.
Maximum value 100000000000 (1011) XAH. That's 100000000000000000 (1017) "drops".	Maximum value 9999999999999999e80.
Precise to the nearest "drop" (0.000001 XAH)	15 decimal digits of precision.
Can't be frozen.	The issuer can freeze balances.
No transfer fees; XAH-to-XAH payments are always direct.	Can take indirect paths with each issuer charging a percentage transfer fee.
Can be used in Payment Channels and Escrow.	Can be used with Payment Channels or Escrow.

For more information, see What is XAH? and Tokens.

Specifying Currency Amounts

Use the appropriate format for the type of currency you want to specify:

• XAH Amounts

• Token Amounts

XAH Amounts

To specify an amount of XAH, use a String Number indicating drops of XAH, where each drop is equal to 0.000001 XAH. For example, to specify 13.1 XAH:

"13100000"

Do not specify XAH as an object.

XAH amounts cannot be negative.

Token Amounts

To specify an amount of a (fungible) token, use an Amount object. This is a JSON object with three fields:

Field	Type	Description
currency	String - Currency Code	Arbitrary currency code for the token. Cannot be XAH.
value	String Number	Quoted decimal representation of the amount of the token. This can include scientific notation, such as 1.23e11 meaning 123,000,000,000. Both e and E may be used. This can be negative when displaying balances, but negative values are disallowed in other contexts such as specifying how much to send.
issuer	String	Generally, the account that issues this token. In special cases, this can refer to the account that holds the token instead (for example, in a Clawback transaction).

Caution: These field names are case-sensitive.

For example, to represent $153.75 US dollars issued by account r9cZA1mLK5R5Am25ArfXFmqgNwjZgnfk59, you would specify:

{
    "currency": "USD",
    "value": "153.75",
    "issuer": "r9cZA1mLK5R5Am25ArfXFmqgNwjZgnfk59"
}

Specifying Without Amounts

In some cases, you need to define an asset (which could be XAH or a token) without a specific amount, such as when defining an order book in the decentralized exchange.

To describe a token without an amount, specify it as a currency object, but omit the value field. For example:

{
  "currency": "TST",
  "issuer": "rP9jPyP5kyvFRb6ZiRghAGw5u8SGAmU4bd"
}

To describe XAH without an amount, specify it as a JSON object with only a currency field. Never include an issuer field for XAH. For example:

{
  "currency": "XAH"
}

String Numbers

XAH Precision

XAH has the same precision as a 64-bit unsigned integer where each unit is equivalent to 0.000001 XAH. It uses integer math, so that any amount less than a full drop is rounded down.

Token Precision

Tokens can represent a wide variety of assets, including those typically measured in very small or very large denominations. This format uses significant digits and a power-of-ten exponent in a similar way to scientific notation. The format supports positive and negative significant digits and exponents within the specified range. Unlike typical floating-point representations of non-whole numbers, this format uses integer math for all calculations, so it always maintains 15 decimal digits of precision. Multiplication and division have adjustments to compensate for over-rounding in the least significant digits.

When sending token amounts in Xahau's peer-to-peer network, servers serialize the amount to a 64-bit binary value.

Tip: For tokens that should not be divisible at all, see Non-Fungible Tokens (NFTs).

Currency Codes

Standard Currency Codes

The standard format for currency codes is a three-character string such as USD. This is intended for use with ISO 4217 Currency Codes. The following rules apply:

• Currency codes must be exactly 3 ASCII characters in length. The following characters are permitted: all uppercase and lowercase letters, digits, as well as the symbols ?, !, @, #, $, %, ^, &, *, <, >, (, ), {, }, [, ], and |.

• Currency codes are case-sensitive.

• The currency code XAH (all-uppercase) is disallowed. Real XAH typically does not use a currency code in Xahau's protocol.

At the protocol level, this format is serialized into a 160-bit binary value starting with 0x00.

Nonstandard Currency Codes

You can also use a 160-bit (40-character) hexadecimal string such as 015841551A748AD2C1F76FF6ECB0CCCD00000000 as the currency code. To prevent this from being treated as a "standard" currency code, the first 8 bits MUST NOT be 0x00.

Deprecated: Some previous versions of ripple-lib supported an "interest-bearing" or "demurraging" currency code type. These codes have the first 8 bits 0x01. Demurraging / interest-bearing currencies are no longer supported, but you may find them in ledger data. For more information, see Demurrage.