order expiration change

BEP45

BEP 67

change format

BEP67.md

@@ -0,0 +1,48 @@
+# BEP-67: Differential Order Expiration
+
+- [BEP-67: Differential Order Expiration](#bep-67-differential-order-expiration)
+  - [1. Summary](#1-summary)
+  - [2. Abstract](#2-abstract)
+  - [3. Status](#3-status)
+  - [4. Motivation](#4-motivation)
+  - [5. Specification](#5-specification)
+    - [5.1 Order Expiration](#51-order-expiration)
+    - [5.2 Change Impact](#52-change-impact)
+  - [6. License](#6-license)
+
+## 1. Summary 
+
+This BEP describes an enhancement of the [Order Expiration](https://docs.binance.org/faq.html#what-is-order-expire).  
+
+## 2. Abstract
+
+Currently orders on Binance Chain will be expired after 72 hours. This may lead to high frequency of order placement, which is not very convenient to users. 
+The solution is to keep orders in the best 500 price level for 30 days rather than 72 hours.
+
+## 3. Status
+
+This BEP is under specification.
+
+## 4. Motivation
+
+Some users want to keep their open orders more than 3 days so that they do not need re-create their cancelled orders every three days. 
+
+
+## 5. Specification
+
+###  5.1 Order Expiration
+In the breath block (1st block after UTC 00:00 every day), orders which have been in order book for longer than 72 hours will be removed from order book and marked as 'expired'. 
+After the implementation of this BEP, those orders in the best 500 price levels on both ask and bid side will be expired after 30 days instead of 72 hours. Meanwhile, the expiration fee is unchanged.
+
+
+###  5.2 Change Impact
+####  5.2.1 Impact on User
+For those users who follow current strict 3-day expiration time, they may need change their order placement strategy.
+####  5.2.2 Impact on Binance Chain
+There could be more orders in node memory. So the compulsory expiration is introduced for the orders older than 30 days.
+## 6. License
+
+The content is licensed under [CC0](https://creativecommons.org/publicdomain/zero/1.0/).
+
+
+

README.md

@@ -14,3 +14,4 @@ Here are the list of subjects of BEPs:
 * [BEP-12](BEP12.md): Introduce Customized Scripts and Transfer Memo Validation
 * [BEP-18](BEP18.md): State sync enhancement
 * [BEP-19](BEP19.md): Introduce Maker and Taker for Match Engine
+* [BEP-67](BEP67.md): Differential Order Expiration