PT, YT, and attnUSD – Technical Design

This page describes the lower-level objects that sit under attn’s user-facing concepts:

Revenue account → the underlying cashflow source.
Principal Token (PT) → the “principal leg” of a revenue position.
Yield Token (YT) → the “cashflow leg” between now and a defined maturity.
attnUSD → a vault share token that holds a portfolio of PT/YT positions and stablecoins.

The goals are to:

standardise how revenue-backed positions are represented on-chain,
make them composable with fixed-income infrastructure on Solana, using Exponent Finance’s “Standardised Yield” (SY) framework for PT/YT representation,
and give LPs and integrators a clear picture of what backs attnUSD.

This is a conceptual specification rather than a formal program spec.

1. Objects and terminology

1.1 Revenue Account

A Revenue Account is a jointly controlled onchain vault (typically a Squads Safe) that:

receives protocol / creator / network revenues,
enforces routing rules when one or more financing positions are active,
can deploy unencumbered balances into safe yield sources.

From the PT/YT system’s perspective, a revenue account is:

a source of cashflows over time,
associated with a specific project and risk profile,
referenced by an identifier rev_id.

1.2 Revenue-Bearing Position (RBP)

To interface with yield-stripping infra, we define a logical Revenue-Bearing Position (RBP):

a token or virtual position whose value derives from the discounted future cashflows of a revenue account over some horizon.

In practice:

the RBP is an internal abstraction (not necessarily a freely transferable token),
attn can wrap it as a standardised “yield-bearing token” type if the infra provider expects that (e.g. an SY-like token in Exponent’s model).

Each RBP is tagged by:

an underlying revenue account rev_id,
a maturity date T,
a notional amount (e.g. a USD-equivalent measure of expected flows).

1.3 Principal Token (PT)

A Principal Token (PT) is an SPL token that represents the “principal leg” of an RBP:

1 PT is designed to redeem for a fixed principal amount of the underlying at maturity T,
PTs are non-yield-bearing: they do not accrue revenue between t0 (position open) and T,
their market value before maturity reflects:
- time to maturity,
- discount rates,
- perceived credit / revenue risk.

For attn, PT is primarily a bookkeeping and hedging tool:

the protocol can hold PTs to represent the “residual” after selling cashflows,
or PTs can be used in future structured products (e.g. PT/USDC pools).

1.4 Yield Token (YT)

A Yield Token (YT) is an SPL token that represents the “yield leg” of an RBP:

1 YT is entitled to the cashflows generated by the underlying RBP between t0 and maturity T,
YTs generally have no claim at or after maturity (their value decays to 0 as t → T),
their market value reflects:
- expected future revenue over the period,
- risk of underperformance or default,
- time to maturity and discount rates.

In attn, the YT is the key object for revenue-backed positions:

advances and credit lines largely correspond to allocating YT (or YT-like flows) to capital providers,
the project retains PT (and often some YT-like upside beyond what is pledged).

1.5 attnUSD

attnUSD is the share token of a vault that holds:

a basket of stablecoins (USDC, USDT, USDe, USDC+),
a portfolio of PT and YT positions across many revenue accounts,
and optionally some buffer / reserve assets.

Let:

NAV(t) = total marked value of the vault’s assets minus liabilities at time t,
S(t) = total supply of attnUSD at time t.

Then:

the attnUSD share price is P(t) = NAV(t) / S(t),
LPs deposit stablecoins to mint attnUSD at or near P(t),
LPs burn attnUSD to withdraw a pro-rata share of the underlying.

Yield for LPs is encoded in how P(t) changes over time.

2. Yield-stripped representation of revenue positions

2.1 Mapping a position into PT/YT

When a revenue-backed position is opened, we conceptually:

Define the position term:
- a maturity T,
- a target repayment amount R_target (principal + fees),
- a revenue share schedule (e.g. α% of relevant revenues between t0 and T),
- a priority level (waterfall position).
Construct an RBP representing the cashflows:
- from the relevant share(s) of the revenue account,
- over the window [t0, T],
- up to the cap R_target (where applicable).
Perform a yield strip:
- mint PT_position representing “principal” at T,
- mint YT_position representing the project’s obligations on revenue flows over [t0, T].

In an Exponent-style implementation:

the RBP can be represented as an SY token (standardised yield-bearing token),
PT and YT are then derived from that SY position via the infra’s stripping logic,
attn treats those PT/YT tokens as the canonical representation of the position on-chain.

For many attn positions:

the economic exposure is heavily concentrated in the YT leg,
PT may be structured to represent residual claims or collateral reversion after maturity.

2.2 Lifecycle of YT

YT behaviour over time:

At t0 (position open), YT has full exposure to future revenue in the position window.
As revenues arrive and are routed to the position:
- some portion of the economic value “realises”,
- the outstanding risk on the YT’s remaining flows decreases.
At or after T:
- YT either has been fully paid through R_target being reached,
- or whatever shortfall exists is recognised as a loss for the YT holder.

In many designs:

YT ceases to have any claim after T; it is economically exhausted,
if the system allows, some “tail” recovery can occur via restructuring, but that is a separate action.

2.3 Lifecycle of PT

PT behaviour over time depends on how much of the underlying is tied to the position:

It can be configured to:
- represent residual claims to revenue beyond T,
- represent a right to any unencumbered portion of the RBP at maturity,
- or be a purely internal hedging instrument.

Because attn is focused on finite-horizon positions backed by live revenues, PT usage in early versions may be constrained to:

internal accounting of “what principal is expected to come back at maturity”,
future structured products (e.g. principal-only pools for more conservative LPs).

3. One-off revenue advances under the hood

Consider a one-off advance:

Project wants upfront A USDC.
attn sets:
- revenue share α (e.g. 30%),
- term [t0, T] (e.g. 6 weeks),
- target repayment R_target = A + fees.

Onchain:

A position record is created referencing:
- the project’s revenue account,
- (α, T, R_target),
- priority in the repayment waterfall.
A corresponding RBP_position is defined and yield-stripped into (PT_position, YT_position).
Capital match:
- the attnUSD vault (or another LP source) buys YT_position from the position at a price close to A,
- A USDC (minus any origination costs) is sent to the project,
- YT_position is held by the vault as an asset.
As revenues hit the revenue account:
- the routing logic applies α% of relevant flows to R_position,
- once R_position >= R_target, the position is closed and YT_position is considered fully paid.

The vault’s return on this position is:

realised cashflows from the revenue share,
minus A and any allocated losses / costs,
expressed in how the YT position is marked over time and finally settled.

4. Revenue-backed credit lines under the hood

A revenue-backed credit line is a standing facility rather than a single static strip.

Parameters may include:

a maximum limit L_max,
a base revenue share α applied when the line is drawn,
dynamic adjustments based on utilisation and performance.

Lifecycle:

Facility setup:
- a facility object is created pointing to the revenue account,
- risk limits and revenue share curves are stored,
- no PT/YT is minted yet (no drawn amount).
Draw events:
- when the project draws ΔA from the line,
- the system creates a new “draw tranche”:
  - with its own maturity T_i and R_target_i,
  - a corresponding (PT_i, YT_i) strip,
  - purchased by the vault in exchange for ΔA.
Repayment:
- revenue routing applies the facility’s rules to current utilisation,
- cashflows are assigned to each YT_i until its R_target_i is reached,
- drawn balance reduces accordingly; the facility can be reused.

From the vault’s perspective:

a credit line is a collection of YT tranches with staggered terms and exposures,
each tranche can be marked and risk-managed separately,
line-level limits ensure no single facility dominates the portfolio.

5. attnUSD vault mechanics

5.1 Asset set

The attnUSD vault can hold:

Stablecoins – USDC, USDT, USDe, USDC+.
Yield-stripped positions – PT and YT from many revenue accounts and facilities.
Reserves / buffers – safe assets or idle stables for liquidity management.

5.2 NAV and pricing

At any time t, the vault computes:

NAV_stables(t) – value of pure stablecoin holdings (usually at par, unless impaired).
NAV_PT(t) – value of PT positions, using conservative discount curves and risk haircuts.
NAV_YT(t) – value of YT positions, based on:
- realised revenue to date,
- projected future revenue over remaining terms,
- probabilistic default and recovery assumptions.
NAV_reserves(t) – any additional reserve assets.

Then:

NAV(t) = NAV_stables(t) + NAV_PT(t) + NAV_YT(t) + NAV_reserves(t)
share price P(t) = NAV(t) / S(t).

5.3 Minting and redemption

When an LP deposits stablecoins:

they send stables into the vault,
the vault mints new attnUSD such that:
- the LP receives attnUSD at or very close to current P(t),
- minor deviations can be used to cover minting / redemption costs.

When an LP redeems attnUSD:

they burn attnUSD,
the vault returns a mix of:
- stablecoins,
- potentially very liquid PT/YT if redemptions are large (later phases),
again, targeting withdrawals at or near current P(t).

5.4 Losses and recoveries

If a set of YT positions underperforms badly:

expected cashflows drop,
their marked value is written down,
NAV(t) decreases, and so does P(t).

Recoveries (e.g. renegotiations, late revenue, collateral unwinds) can:

partially restore YT or PT value,
be reflected in higher NAV(t) and P(t) later.

attnUSD is not intended to behave like a guaranteed 1:1 stable.

6. Relationship to user-facing concepts

The PT/YT and vault system maps back to the higher-level language as follows:

“Revenue account”
→ underlying source of cashflows referenced by RBPs.
“Advance”
→ a finite-horizon YT position sold to the vault, plus any internal PT held as residual.
“Credit line”
→ a collection of YT tranches spanning multiple draws, governed by a single facility.
“attnUSD yield”
→ aggregate performance of:
- YT positions across all positions,
- any PT appreciation / hedge,
- and base yield on underlying balances.

This separation allows:

front-end UX to stay in plain business terms (advance, line, revenue share),
back-end risk and liquidity management to operate in a standardised fixed-income vocabulary (PT, YT, maturities, haircuts, NAV).

7. Implementation and infra notes

The yield-stripping mechanism (PT/YT minting and redemption) is implemented using Exponent Finance’s Standardised Yield (SY) infra on Solana.
attn treats this infra as:
- the canonical way to turn a yield-bearing position (here, revenue) into PT/YT,
- a shared standard that other protocols can integrate with,
- an auditable onchain representation of credit exposures.

In early versions, some of these details may be simplified or kept internal:

PT may be non-transferable or rarely used,
only a subset of YT positions may be exposed to external secondary markets,
pricing models will err on the side of conservative haircuts and shorter maturities.

As the system matures, PT/YT and attnUSD can form the basis for:

secondary markets for specific revenue bonds,
structured products (e.g. PT-only pools for lower-risk LPs),
integrations with other protocols that understand standardised yield tokens.

The invariant across versions is:

every advance or credit line is backed by explicit, tokenised claims on well-defined revenue streams,
and attnUSD only takes risk through these tokenised positions and stablecoins, not through opaque leverage or unrelated exposures.