doc: periodic txns, automated postings edits

[ci skip]

hledger-lib/hledger_journal.m4.md

@@ -877,52 +877,57 @@ It can include journal, timeclock or timedot files, but not CSV files.
 
 # Periodic transactions
 
-A periodic transaction starts with a tilde ‘~’ in place of a date followed by a [period expression](manual.html#period-expressions):
+Periodic transactions are a kind of rule with a dual purpose: they can specify 
+recurring future transactions (with `--forecast`), or budget goals (with `--budget`). 
+They look a bit like a transaction, except the first line is a tilde (`~`) followed by a [period expression](manual.html#period-expressions):
 ```journal
 ~ weekly
   assets:bank:checking   $400 ; paycheck
   income:acme inc
 ```
 
-Periodic transactions are used for forecasting and budgeting only, they have no effect unless the `--forecast` or `--budget` flag is used.
+With `--forecast`, each periodic transaction rule generates recurring "forecast" transactions at the specified interval, 
-With `--forecast`, each periodic transaction rule generates recurring forecast transactions
+beginning the day after the latest recorded journal transaction (or today, if there are no transactions)
-at the specified interval, beginning the day after the last recorded journal transaction
+and ending 6 months from today (or at the report end date, if specified).
-and ending 6 months from today, or at the specified report end date.
+
-With `balance --budget`, each periodic transaction declares recurring budget goals for one or more accounts.   
+With `balance --budget`, each periodic transaction declares recurring budget goals for the specified accounts.
+Eg the example above declares the goal of receiving $400 from `income:acme inc`
+(and also, depositing $400 into `assets:bank:checking`) every week.
+
 For more details, see:
-[balance > Budgeting](manual.html#budgeting), 
+[balance: Budgeting](manual.html#budgeting)
+and
 [Budgeting and Forecasting](budgeting-and-forecasting.html).
 
-# Automated posting rules
+# Automated postings
 
-Automated posting rule starts with an equal sign '=' in place of a date, followed by a [query](manual.html#queries):
+Automated postings are postings added automatically by rule to certain transactions (with `--auto`).
+An automated posting rule looks like a transaction where the first line is an equal sign (`=`) followed by a [query](manual.html#queries):
 ```journal
 = expenses:gifts
     budget:gifts  *-1
     assets:budget  *1
 ```
 
-When `--auto` option is specified on the command line, automated posting rule will add its postings to all transactions that match the query.
+The posting amounts can be of the form `*N`, which means "the amount of the matched transaction's first posting, multiplied by N".
+They can also be ordinary fixed amounts. 
+Fixed amounts with no commodity symbol will be given the same commodity as the matched transaction's first posting.
 
-If amount in the automated posting rule includes commodity name, new posting will be made in the given commodity, otherwise commodity of the matched transaction will be used.
+This example adds a corresponding (unbalanced) budget posting to every transaction involving the `expenses:gifts` account:
-
-When amount in the automated posting rule begins with the '*', amount will be treated as a multiplier that is applied to the amount of the first posting in the matched transaction.
-
-In example above, every transaction in `expenses:gifts` account will
-have two additional postings added to it: amount of the original gift
-will be debited from `budget:gifts` and credited into `assets:budget`:
 ```journal
-; Original transaction
+= expenses:gifts
+    (budget:gifts)  *-1
+
 2017-12-14
   expenses:gifts  $20
   assets
-
+```
-; With automated postings applied
+```shell
+$ hledger print --auto
 2017/12/14
     expenses:gifts             $20
     assets
-    budget:gifts              $-20
+    (budget:gifts)            $-20
-    assets:budget              $20
 ```
 
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