Defining a posting
A posting is defined as followed:COIN with no scaling value, and the amount is 100.
Postings with balance
You can omit the amount of an asset in a posting and replace it with a*. This is used when you want to move all of the assets of the accounts in the source block to the ones destination block.
USD/2 asset from the @order:1234 account. 10% of the @order:1234 balance is moved to the @platform:fees account, and the remaining 90% is moved to the @merchant:5678 account.