Decimals of CKB

[Keith-CY]

I was always confused with CKB's decimals between layer1 and layer2, so I open this discussion to make it clear.

Now there're 3 places to display the amount of CKB.

1. deposit/withdraw CKB
2. Transfer CKB
3. User's balance in CKB

I thought there were two CKB in layer 2, the one used in transfers between users(called CKB), and the other one used to pay the transaction fee(called gCKB).

The CKB transferred between users has deciamls 8, which is the same as that of CKB in layer 1, while the gCKB used to pay fee has decimals 18.

In this case, when user A deposits 1 CKB(10^8 shannons) from layer 1 to layer 2, 1 CKB(10^8 shannons) will be minted on layer 2, and the record will be displayed as follow,

type    |  value(CKB)
deposit |    1

and user A's balance is 1 CKB

then user A transfers 0.5 * 10^8 shannons(0.5 CKB) to others with 100 shannons(100 * 10^-18 pCKB), the record will be displayed as follow

type | value(CKB) | fee(pCKB)
send | 0.5        | 100 * 10^-18

user A's balance turns into 1 - 0.5 - 100 * 10^-8 = 0.49999999 CKB

This is my understanding of CKB and pCKB before.

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Today I've learned that there's only one CKB in layer 2, gCKB, which has decimals 18. When 1 CKB(10**8 shannons) in layer 1 is deposited to layer 2, 1 gCKB(10^18 gshannons) will be minted. Then the example mentioned above becomes

type    |  value(gCKB)
deposit |  1

user A's balance is 1 gCKB

type  |    value(gCKB)         | fee(gCKB)
send  |    0.5 * 10^-10       |  100 * 10^-18 

user A's balance is 1 - 0.5 * 10^-10 - 100 * 10^18 = 0.9999999999499999 gCKB

Is the second case correct? @Flouse @gpBlockchain

[Keith-CY]

cc @classicalliu, @zeroqn

[Keith-CY]

Confirmed with @gpBlockchain and @classicalliu that the second case is correct

[Flouse]

Yes, there's only one CKB in layer 2, called gCKB or pCKB, which decimals is 18.

Related PRs

godwoken

• BREAKING CHANGE: change ckb decimal to 18 godwokenrises/godwoken#675

godwoken-scripts

• BREAKING CHANGE: change ckb decimal to 18 godwokenrises/godwoken-scripts#118

godowken-polyjuice

• BREAKING CHANGE: change ckb decimal to 18 godwokenrises/godwoken-polyjuice#146