diff --git a/hledger-lib/Hledger/Reports/PostingsReport.hs b/hledger-lib/Hledger/Reports/PostingsReport.hs
index d0fcdd662..b09097d55 100644
--- a/hledger-lib/Hledger/Reports/PostingsReport.hs
+++ b/hledger-lib/Hledger/Reports/PostingsReport.hs
@@ -177,7 +177,7 @@ tests_summarisePostingsByInterval = [
 -- interval's end date attached with a tuple.
 type SummaryPosting = (Posting, Maybe Day)
 
--- | Given a date span (representing a reporting interval) and a list of
+-- | Given a date span (representing a report interval) and a list of
 -- postings within it, aggregate the postings into one summary posting per
 -- account.
 --
diff --git a/hledger/Hledger/Cli/Balance.hs b/hledger/Hledger/Cli/Balance.hs
index a7ef7caf9..fb37c9e0d 100644
--- a/hledger/Hledger/Cli/Balance.hs
+++ b/hledger/Hledger/Cli/Balance.hs
@@ -9,7 +9,7 @@ Here is a description/specification for the balance command.  See also
 
 /Basic balance report/
 
-With no reporting interval (@--monthly@ etc.), hledger's balance
+With no report interval (@--monthly@ etc.), hledger's balance
 command emulates ledger's, showing accounts indented according to
 hierarchy, along with their total amount posted (including subaccounts).
 
diff --git a/hledger/Hledger/Cli/CliOptions.hs b/hledger/Hledger/Cli/CliOptions.hs
index d7a89dfc6..6b9180d49 100644
--- a/hledger/Hledger/Cli/CliOptions.hs
+++ b/hledger/Hledger/Cli/CliOptions.hs
@@ -133,7 +133,7 @@ reportflags = [
  ,flagNone ["monthly","M"]   (setboolopt "monthly") "multiperiod/multicolumn report by month"
  ,flagNone ["quarterly","Q"] (setboolopt "quarterly") "multiperiod/multicolumn report by quarter"
  ,flagNone ["yearly","Y"]    (setboolopt "yearly") "multiperiod/multicolumn report by year"
- ,flagReq  ["period","p"]    (\s opts -> Right $ setopt "period" s opts) "PERIODEXP" "set start date, end date, and/or reporting interval all at once (overrides the flags above)"
+ ,flagReq  ["period","p"]    (\s opts -> Right $ setopt "period" s opts) "PERIODEXP" "set start date, end date, and/or report interval all at once (overrides the flags above)"
  ,flagNone ["date2"]         (setboolopt "date2") "show, and make -b/-e/-p/date: match, secondary dates instead"
 
  ,flagNone ["cleared","C"]   (setboolopt "cleared") "include only cleared postings/txns"
diff --git a/hledger/Hledger/Cli/Histogram.hs b/hledger/Hledger/Cli/Histogram.hs
index 93fc2e8d2..02e3ffc80 100644
--- a/hledger/Hledger/Cli/Histogram.hs
+++ b/hledger/Hledger/Cli/Histogram.hs
@@ -33,7 +33,7 @@ activitymode = (defCommandMode $ ["activity"] ++ aliases) {
 barchar :: Char
 barchar = '*'
 
--- | Print a histogram of some statistic per reporting interval, such as
+-- | Print a histogram of some statistic per report interval, such as
 -- number of postings per day.
 histogram :: CliOpts -> Journal -> IO ()
 histogram CliOpts{reportopts_=ropts} j = do
diff --git a/hledger/Hledger/Cli/Register.hs b/hledger/Hledger/Cli/Register.hs
index 7368f70a3..ad8ecc8ed 100644
--- a/hledger/Hledger/Cli/Register.hs
+++ b/hledger/Hledger/Cli/Register.hs
@@ -111,7 +111,7 @@ tests_postingsReportAsText = [
 -- If description's width is specified, account will use the remaining space.
 -- Otherwise, description and account divide up the space equally.
 --
--- With a reporting interval, the layout is like so:
+-- With a report interval, the layout is like so:
 -- @
 -- <---------------- width (specified, terminal width, or 80) -------------------->
 -- date (21)              account                        amount (12)   balance (12)
diff --git a/hledger/doc/options.m4.md b/hledger/doc/options.m4.md
index 51eae9e2f..260e02869 100644
--- a/hledger/doc/options.m4.md
+++ b/hledger/doc/options.m4.md
@@ -101,11 +101,11 @@ Examples:
 `today`, `yesterday`, `tomorrow`
 ---
 
-## Reporting interval
+## Report interval
 
-A reporting interval can be specified so that commands like
+A report interval can be specified so that commands like
 [register](#register), [balance](#balance) and [activity](#activity) will divide their
-reports into multiple report periods.  The basic intervals can be
+reports into multiple subperiods.  The basic intervals can be
 selected with one of `-D/--daily`, `-W/--weekly`, `-M/--monthly`,
 `-Q/--quarterly`, or `-Y/--yearly`.  More complex intervals may be
 specified with a period expression.
@@ -113,11 +113,9 @@ specified with a period expression.
 ## Period expressions
 
 The `-p/--period` option accepts period expressions, a shorthand way
-of expressing a start date, end date, and or reporting interval all at
-once. Note a period expression on the command line will cause any other date
-flags (`-b`/`-e`/`-D`/`-W`/`-M`/`-Q`/`-Y`) to be ignored.
+of expressing a start date, end date, and/or report interval all at
+once.
 
-hledger's period expressions are similar to Ledger's, though not identical.
 Here's a basic period expression specifying the first quarter of 2009. Note,
 hledger always treats start dates as inclusive and end dates as exclusive:
 
@@ -161,23 +159,41 @@ like so:
 `-p "2009/1/1"`       just that day;    equivalent to "2009/1/1 to 2009/1/2"
 --------------------- ------------------------------------------------------
 
-Period expressions can also start with (or be) a reporting interval:
-`daily`, `weekly`, `monthly`, `quarterly`, `yearly`, or one of the
-`every ...` expressions below. Optionally the word `in` may appear
-between the reporting interval and the start/end dates.
-Examples:
+The argument of `-p` can also begin with, or be, a [report interval](#report-interval) expression.
+The basic report intervals are `daily`, `weekly`, `monthly`, `quarterly`, or `yearly`, 
+which have the same effect as the `-D`,`-W`,`-M`,`-Q`, or `-Y` flags.
+Between report interval and start/end dates (if any), the word `in` is optional.
+Examples: 
 
 ------------------------------------------
 `-p "weekly from 2009/1/1 to 2009/4/1"`
-`-p "monthly in 2008"`
-`-p "bimonthly from 2008"`
+`-p "monthly in 2008"`                          
 `-p "quarterly"`
+------------------------------------------
+
+The following more complex report intervals are also supported:
+`biweekly`, 
+`bimonthly`,
+`every N days|weeks|months|quarters|years`,
+`every Nth day [of month]`,
+`every Nth day of week`.
+
+Examples:
+
+------------------------------------------
+`-p "bimonthly from 2008"`
 `-p "every 2 weeks"`
 `-p "every 5 days from 1/3"`
-`-p "every 15th day of month"`
-`-p "every 4th day of week"`
 ------------------------------------------
 
+Show historical balances at end of 15th each month (N is exclusive end date):
+
+`hledger balance -H -p "every 16th day"`
+
+Group postings from start of wednesday to end of next tuesday (N is start date and exclusive end date):
+
+`hledger register checking -p "every 3rd day of week"`   
+
 ## Regular Expressions
 
 hledger uses [regular expressions](http://www.regular-expressions.info) in a number of places: