The purpose of this option is to add special "<Rounding>" postings, to
ensure that a regiter's running total is *always* the sum of its
postings. Within --rounding, these adjustment postings are missing,
which was the behavior in Ledger 2.x. It can be orders of magnitude
slower to turn it on for large reports with many commodities.
When this option is on, then in balance report which show market values,
any gains or losses in value will be balanced into a pair of accounts
called Equity:Unrealized Gains and Equity:Unrealized Losses.
This allows for value expressions to be used which reference the
incoming posting, for example:
= Income:Clients:
(Liabilities:Taxes:VAT1) (floor(amount) * 1)
(Liabilities:Taxes:VAT2) 0.19
2009/07/27 * Invoice
Assets:Bank:Checking $1,190.45
Income:Clients:ACME_Inc
The automated posting for VAT1 will use the floored amount multiplied by
a factor, while the posting for VAT2 multiples the whole amount as
before.
This fits better with the --amount and --total options, which both
change the amount and total used for calculation. Same with --account:
it happens after filtering, but before calculation so that balance
reports look as you'd expect.
This is necessary because sometimes, a post from one account will get
reported as though it were in another account (this happens with
--budget, to show child account postings within their parent account).
In that case, the account needs to remember which postings have been
reported as being within it, so that it can add these amounts to its own
total in the balance report.
It is now a full parser that parses report queries directly into value
expression trees. These then get rendered into text so that other
options may extend the expression.
This sets Ledger's notion of the "current time" to the given date. This
makes it possible to have stable output from budgeting and forecasting
reports, for the sake of baseline tests.
