# 7.6 EVT Pools (National Pool / Store Pool)

EVT is not designed to come from anywhere with unlimited supply.\
The amount of EVT that can be excavated is managed through a two-layer structure: the **National Pool** and the **Store Pool**.

This page explains the pool structure that serves as the “source” of EVT.

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### What you’ll learn on this page

* What the National Pool is (reserves, remaining balance, updates)
* Which country’s pool is consumed
* How it relates to the Store Pool (80% / 20%)
* How remaining balance affects difficulty (how easy it is to excavate)

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### 1) What is the National EVT Pool? (Reserves = remaining balance for the country)

The **National EVT Pool** represents the total amount of EVT that can be excavated within a country (i.e., its reserves).

* As users excavate EVT, the country’s remaining pool balance decreases.
* Each country is managed independently and does not share supply with other countries.

#### Update timing

National Pool status is updated **daily at 00:00 UTC**.

In the app, users can check:

* Store unlock status
* National remaining balance (pool status)

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### 2) Country-Based Management: Which Country’s Pool Is Consumed?

EVT pools are managed **independently by country**.

When you excavate EVT, the pool that is consumed is the one belonging to the country of **the store where you performed the BIND**.

Examples:

* BIND at a store in Japan → Japan’s National Pool is consumed
* BIND at a store in France → France’s National Pool is consumed

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### 3) Two-Layer Structure: National Pool (80%) / Store Pool (20%)

EVT is managed through a two-layer structure:

* **National Pool: 80%** (the base excavation allocation)
* **Store Pool: 20%** (a store-level additional allocation)

The “80% / 20%” refers to the **design ratio of EVT supply sources**.\
Which pool is actually applied to excavation depends on the store’s unlock status, remaining balance, and eligibility conditions.

#### What is the Store Pool?

The Store Pool is a store-level additional allocation that becomes active **only when a specific user unlocks excavation rights for that store by using a Right Scroll (Excavation Right NFT).**

In other words, “a store is unlocked” means: the user who exercised a Right Scroll for that store is granted access to the Store Pool (additional allocation).\
(It does **not** mean the Store Pool becomes available to all users.)

* The Store Pool is managed separately from the National Pool.
* The Store Pool can be used for excavation only when the right-holder meets the BIND requirements at that store.

#### When does it become “National Pool only”?

In the following cases, excavation at that store is based on the **National Pool portion (80%) only**:

* You have not exercised a Right Scroll for that store and do not hold Store Pool rights.
* The Store Pool balance has reached zero (depleted).

*Note: Only one user can exercise a Right Scroll for the same store (see 7.9 for details).*

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### 4) How does “more remaining balance = easier excavation” work?

SyFu reflects the following design principle in its difficulty system:

> The more reserves remain, the easier excavation is.\
> As reserves decrease, excavation becomes harder.

#### Difficulty changes based on National Pool consumption ratio

When the National Pool consumption ratio exceeds certain thresholds,\
excavation efficiency (difficulty factor) changes in stages.

Example thresholds:

* 50%
* 75%
* 90%

As each threshold is crossed, excavation efficiency is reduced.\
(See 7.7 for details.)

This creates an **automatic balancing mechanism**, where:

* excavation pace naturally slows as depletion progresses
* sudden supply expansion is suppressed

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### Summary

EVT is managed through a layered control structure:

* Country-level reserves management (National Pool)
* Store-level excavation expansion (Store Pool)
* Difficulty adjustment based on the consumption ratio

Because of this structure, EVT is not a simple “unlimited issuance token.”\
It is designed to evolve in sync with **remaining balance, ecosystem growth, and participation**.

In the next page (7.7), we explain why EVT can be considered “practically finite,”\
based on the soft cap and stage-based unlocking design.