First we can see the Value 1 tab.  This is the Base currency and has been defined as GBP pounds sterling.  This is the local currency.

In a multi-currency environment Base Currency (Value 1) defaults to 3-Calculated if not entered

Decimal Places refers to the number of decimal places in the amount.

Amount Balancing option can be either manual or automatic for Value 1 Base currency.  If Automatic is selected for Base currency then the Transaction currency must be set to Manual.  Both Base and Transaction currencies can be set to Manual. 

Level is used to prevent very large postings being made by the system, under the guise of rounding errors.  If a posting of a value greater than this amount would be required to make the transaction balance, then an error message will be given, and automatic balancing will not occur.

If Value 1 Base Amount Balancing has been set to Manual, the Balancing Level field will be greyed out.

Net or Losses Account and Gains Account are used as rounding error accounts.  For Base currency and Transaction currency these are used in Ledger Entry and Ledger Import.  For  Reporting/Second Base currency these accounts are used for Ledger Entry, Ledger Import and Ledger Revaluation for global balancing.

Value 2 is a multi-code value.  Therefore the relevant currency code will be entered at Ledger Entry/Import stage.

Posting Rule for Value 2 Transaction currency defaults to 0-undefined, 1-Only present if entered.  However, if Value 1 is defined as the pivot, Value 2 must then be set to 3-Calculated if not entered.

Amount Balancing option can be either Manual or None for Value 2. 

Decimal places for the Transaction currency amount are defined within Currency Codes Setup.

Next we can see the Value 3 tab.  This is the Reporting currency.

Value 3 is a single-code value and so a currency code must be entered here.