> For the complete documentation index, see [llms.txt](https://docs.swivel.finance/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.swivel.finance/developers/ubiquitous-language-v4/ui-language.md).

# UI Language

#### Lend

You can lend `Underlying` assets by placing a `Fixed Yield` order.

#### Order

In the Front End context, an Order is any valid `Market Order` or `Limit Order` placed on a given `Market` to lend, buy or sell `Underlying` or `Token` assets.

#### Orderbook

The table of valid, open `Orders` for a given `Market`

#### Fill

Fill orders are `Orderbook` Orders that fulfill your `Market Order` or `Limit Order` partially or in full.

#### Fixed Yield

A Fixed Yield order uses the Swivel protocol to give the user an immediate yield for lending `Underlying` assets. When a Fixed Yield order is filled, Swivel mints an equal amount of `YT` and `PT` on the `Underlying`, leaving the `PT` in your balance and immediately selling the `YTs` on the `Orderbook`, and returning the `Underlying` to your `Balance`.

#### Amplified Yield (deprecated: 'Floating')

An Amplified Yield order purchases `YTs` from the marketplace and adds them to your `Balance`, where they will continue to earn a variable yield until the given `Market` matures.

#### Sell

You can sell your `YTs` or `PTs` back to the `Orderbook` at any time with a Sell order.

#### Market Order

Placing an `Order` as a `Taker`, transacting at the best available price on the `Orderbook`.

#### Limit Order

Placing an `Order` as a `Maker`, transacting at a determined price for the given order type and `Market`. `Valid` unfilled `Limit Orders` appear in your Open Limit Orders view. Depending on `Order` size and `Orderbook` volume, Limit Orders may be filled partially over an undetermined amount of time.

#### Position

The current state of your balance of `Underlying` and `Token` assets, for all active `Markets` you participate in.

#### Principal

* Buy Amplified Yield -> Principal is amount of yield exposure (YT) purchased.
* Buy Fixed Yield -> Principal is amount of Underlying lent.
* Sell YT -> Principal is amount of YT sold.
* Sell PT -> Principal is amount of PT sold.

#### Premium

* Buy Amplified Yield -> Premium is amount of underlying spent on yield exposure (YT).
* Buy Fixed Yield -> Premium is amount of generated yield, expressed in underlying asset.
* Sell YT -> Premium is the amount of generated yield, expressed in underlying asset.
* Sell PT -> Premium is price per underlying received when full.


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