diff --git a/hledger/hledger.m4.md b/hledger/hledger.m4.md
index 00d16661c..5114ff3f9 100644
--- a/hledger/hledger.m4.md
+++ b/hledger/hledger.m4.md
@@ -698,26 +698,6 @@ Examples:
 | `-p "every 5th November"`    | same                                                     |
 | `-p "every Nov 5th"`         | same                                                     |
 
-Intervals beginning on multiple days of the week can be specified by combining
-`WEEKDAYNAME`s with commas. For example, an expression that starts a new period
-on every standard weekday would be `mon,tue,wed,thu,fri`.  For convenience, the
-special period expressions `weekday` and `weekendday` are effectively
-`mon|tue|wed|thu|fri` and `sat|sun` respectively.
-
-Note that this will generate adjacent but uneven periods so the periods may not
-be as directly comparable. This is probably most useful as a periodic
-transaction (#periodic-transactions).
-
-Examples:
-
-|                              |                                                             |
-|------------------------------|-------------------------------------------------------------|
-| `-p "every mon,fri"`         | periods will be `[Mon, Fri), [Fri, Mon)...`                 |
-| `-p "every mon,wed,fri"`     | periods will be `[Mon, Wed), [Wed, Fri), [Fri, Mon)...`     |
-| `-p "every weekday"`         | periods will be `[Mon], [Tue], [Wed], [Thu], [Fri, Mon)...` |
-| `-p "every weekendday"`      | periods will be `[Sat], [Sun, Sat)...`                      |
-
-
 Show historical balances at end of the 15th day of each month (N is an end date, exclusive as always):
 
 ```shell
@@ -730,6 +710,39 @@ Group postings from the start of wednesday to end of the following tuesday (N is
 $ hledger register checking -p "every 3rd day of week"
 ```
 
+### Periods or dates ?
+
+Report intervals like the above are most often used with `-p|--period`,
+to divide reports into multiple subperiods -
+each generated date marks a subperiod boundary.
+Here, the periods between the dates are what's important.
+
+But report intervals can also be used 
+with `--forecast` to generate future transactions,
+or with `balance --budget` to generate budget goal-setting transactions.
+For these, the dates themselves are what matters.
+
+### Events on multiple weekdays
+
+The `every WEEKDAYNAME` form has a special variant with multiple day names, comma-separated. 
+Eg: `every mon,thu,sat`.
+Also, `weekday` and `weekendday` are shorthand for `mon,tue,wed,thu,fri` and `sat,sun` 
+respectively.
+
+This form is mainly intended for use with `--forecast`, to generate 
+[periodic transactions](#periodic-transactions) on arbitrary days of the week.
+It may be less useful with `-p`, since it divides each week into subperiods 
+of unequal length. (Because gaps between periods are not allowed;
+if you'd like to change this, see [#1632](https://github.com/simonmichael/hledger/pull/1632).)
+
+Examples:
+
+|                              |                                                                                        |
+|------------------------------|----------------------------------------------------------------------------------------|
+| `-p "every mon,wed,fri"`     | dates will be Mon, Wed, Fri; <br>periods will be Mon-Tue, Wed-Thu, Fri-Sun             |
+| `-p "every weekday"`         | dates will be Mon, Tue, Wed, Thu, Fri; <br>periods will be Mon, Tue, Wed, Thu, Fri-Sun |
+| `-p "every weekendday"`      | dates will be Sat, Sun; <br>periods will be Sat, Sun-Fri                               |
+
 # DEPTH
 
 With the `--depth NUM` option (short form: `-NUM`),