diff --git a/Makefile b/Makefile
index cbbc3f79e..b28168b33 100644
--- a/Makefile
+++ b/Makefile
@@ -63,7 +63,7 @@ regression-test: build
 # ----------------------------------------------------------------
 # Formatting
 # go fmt ./... finds experimental C files which we want to ignore.
-fmt:
+fmt format:
 	-go fmt ./cmd/...
 	-go fmt ./internal/pkg/...
 	-go fmt ./regression_test.go
diff --git a/docs/src/manpage.md b/docs/src/manpage.md
index a143634ff..eee87469b 100644
--- a/docs/src/manpage.md
+++ b/docs/src/manpage.md
@@ -1933,6 +1933,7 @@ MILLER(1)                                                            MILLER(1)
          ewma       Exponentially weighted moving average over successive records
          from-first Compute differences in field(s) from first record
          ratio      Compute ratios in field(s) between successive records
+         rprod      Compute running products of field(s) between successive records
          rsum       Compute running sums of field(s) between successive records
          shift      Alias for shift_lag
          shift_lag  Include value(s) in field(s) from the previous record, if any
@@ -3337,5 +3338,5 @@ MILLER(1)                                                            MILLER(1)
 
 
 
-                                  2023-03-06                         MILLER(1)
+                                  2023-03-12                         MILLER(1)
 </pre>
diff --git a/docs/src/manpage.txt b/docs/src/manpage.txt
index da217c86f..72c8a2c67 100644
--- a/docs/src/manpage.txt
+++ b/docs/src/manpage.txt
@@ -1912,6 +1912,7 @@ MILLER(1)                                                            MILLER(1)
          ewma       Exponentially weighted moving average over successive records
          from-first Compute differences in field(s) from first record
          ratio      Compute ratios in field(s) between successive records
+         rprod      Compute running products of field(s) between successive records
          rsum       Compute running sums of field(s) between successive records
          shift      Alias for shift_lag
          shift_lag  Include value(s) in field(s) from the previous record, if any
@@ -3316,4 +3317,4 @@ MILLER(1)                                                            MILLER(1)
 
 
 
-                                  2023-03-06                         MILLER(1)
+                                  2023-03-12                         MILLER(1)
diff --git a/docs/src/reference-dsl-differences.md b/docs/src/reference-dsl-differences.md
index 7a21df6c1..6168ca6cc 100644
--- a/docs/src/reference-dsl-differences.md
+++ b/docs/src/reference-dsl-differences.md
@@ -261,4 +261,4 @@ Miller has the verbs
 [`json-stringify`](reference-verbs.md#json-stringify), and the DSL functions
 [`json_parse`](reference-dsl-builtin-functions.md#json_parse) and
 [`json_stringify`](reference-dsl-builtin-functions.md#json_stringify).
-In some other lannguages these are called `json_decode` and `json_encode`.
+In some other languages these are called `json_decode` and `json_encode`.
diff --git a/docs/src/reference-dsl-differences.md.in b/docs/src/reference-dsl-differences.md.in
index 417867645..b71282b9f 100644
--- a/docs/src/reference-dsl-differences.md.in
+++ b/docs/src/reference-dsl-differences.md.in
@@ -219,4 +219,4 @@ Miller has the verbs
 [`json-stringify`](reference-verbs.md#json-stringify), and the DSL functions
 [`json_parse`](reference-dsl-builtin-functions.md#json_parse) and
 [`json_stringify`](reference-dsl-builtin-functions.md#json_stringify).
-In some other lannguages these are called `json_decode` and `json_encode`.
+In some other languages these are called `json_decode` and `json_encode`.
diff --git a/docs/src/reference-verbs.md b/docs/src/reference-verbs.md
index 6d4cf6731..db6c1a644 100644
--- a/docs/src/reference-verbs.md
+++ b/docs/src/reference-verbs.md
@@ -20,14 +20,14 @@ Verbs are the building blocks of how you can use Miller to process your data.
 When you type
 
 <pre class="pre-highlight-in-pair">
-<b>mlr --icsv --opprint sort -n quanity then head -n 4 example.csv</b>
+<b>mlr --icsv --opprint sort -n quantity then head -n 4 example.csv</b>
 </pre>
 <pre class="pre-non-highlight-in-pair">
-color  shape    flag  k index quantity rate
-yellow triangle true  1 11    43.6498  9.8870
-red    square   true  2 15    79.2778  0.0130
-red    circle   true  3 16    13.8103  2.9010
-red    square   false 4 48    77.5542  7.4670
+color  shape    flag k index quantity rate
+red    circle   true 3 16    13.8103  2.9010
+yellow triangle true 1 11    43.6498  9.8870
+yellow circle   true 9 87    63.5058  8.3350
+yellow circle   true 8 73    63.9785  4.2370
 </pre>
 
 the `sort` and `head` bits are _verbs_.  See the [Miller command
@@ -3404,6 +3404,7 @@ Options:
   ewma       Exponentially weighted moving average over successive records
   from-first Compute differences in field(s) from first record
   ratio      Compute ratios in field(s) between successive records
+  rprod      Compute running products of field(s) between successive records
   rsum       Compute running sums of field(s) between successive records
   shift      Alias for shift_lag
   shift_lag  Include value(s) in field(s) from the previous record, if any
diff --git a/docs/src/reference-verbs.md.in b/docs/src/reference-verbs.md.in
index 994c97155..4b022b8dc 100644
--- a/docs/src/reference-verbs.md.in
+++ b/docs/src/reference-verbs.md.in
@@ -4,7 +4,7 @@ Verbs are the building blocks of how you can use Miller to process your data.
 When you type
 
 GENMD-RUN-COMMAND
-mlr --icsv --opprint sort -n quanity then head -n 4 example.csv
+mlr --icsv --opprint sort -n quantity then head -n 4 example.csv
 GENMD-EOF
 
 the `sort` and `head` bits are _verbs_.  See the [Miller command
diff --git a/internal/pkg/entrypoint/entrypoint.go b/internal/pkg/entrypoint/entrypoint.go
index 3b12b2c9c..2655b610f 100644
--- a/internal/pkg/entrypoint/entrypoint.go
+++ b/internal/pkg/entrypoint/entrypoint.go
@@ -90,7 +90,7 @@ func processToStdout(
 //
 // I could have implemented this with a single construction of the transformers
 // and having each transformers implement a Reset() method.  However, having
-// effectively two initalizers per transformers -- constructor and reset method
+// effectively two initializers per transformers -- constructor and reset method
 // -- I'd surely miss some logic somewhere.  With in-place mode being a less
 // frequently used code path, this would likely lead to latent bugs. So this
 // approach leads to greater code stability.
diff --git a/internal/pkg/transformers/step.go b/internal/pkg/transformers/step.go
index c52129fc2..b40aaeed6 100644
--- a/internal/pkg/transformers/step.go
+++ b/internal/pkg/transformers/step.go
@@ -604,6 +604,12 @@ var STEPPER_LOOKUP_TABLE = []tStepperLookup{
 		stepperAllocator:     stepperRatioAlloc,
 		desc:                 "Compute ratios in field(s) between successive records",
 	},
+	{
+		name:                 "rprod",
+		stepperInputFromName: stepperRprodInputFromName,
+		stepperAllocator:     stepperRprodAlloc,
+		desc:                 "Compute running products of field(s) between successive records",
+	},
 	{
 		name:                 "rsum",
 		stepperInputFromName: stepperRsumInputFromName,
@@ -980,6 +986,55 @@ func (stepper *tStepperRatio) process(
 	currec.PutCopy(stepper.outputFieldName, ratio.Copy())
 }
 
+// ================================================================
+type tStepperRprod struct {
+	rprod           *mlrval.Mlrval
+	inputFieldName  string
+	outputFieldName string
+}
+
+func stepperRprodInputFromName(
+	stepperName string,
+) *tStepperInput {
+	return &tStepperInput{
+		name:               stepperName,
+		numRecordsBackward: 0, // doesn't use record-windowing; retains its own pointer
+		numRecordsForward:  0,
+	}
+}
+
+func stepperRprodAlloc(
+	stepperInput *tStepperInput,
+	inputFieldName string,
+	_unused1 []string,
+	_unused2 []string,
+) tStepper {
+	return &tStepperRprod{
+		rprod:           mlrval.FromInt(1),
+		inputFieldName:  inputFieldName,
+		outputFieldName: inputFieldName + "_rprod",
+	}
+}
+
+func (stepper *tStepperRprod) process(
+	windowKeeper *utils.TWindowKeeper,
+) {
+	icur := windowKeeper.Get(0)
+	if icur == nil {
+		return
+	}
+	currecAndContext := icur.(*types.RecordAndContext)
+	currec := currecAndContext.Record
+	currval := currec.Get(stepper.inputFieldName)
+
+	if currval.IsVoid() {
+		currec.PutCopy(stepper.outputFieldName, mlrval.VOID)
+	} else {
+		stepper.rprod = bifs.BIF_times(currval, stepper.rprod)
+		currec.PutCopy(stepper.outputFieldName, stepper.rprod)
+	}
+}
+
 // ================================================================
 type tStepperRsum struct {
 	rsum            *mlrval.Mlrval
diff --git a/man/manpage.txt b/man/manpage.txt
index da217c86f..72c8a2c67 100644
--- a/man/manpage.txt
+++ b/man/manpage.txt
@@ -1912,6 +1912,7 @@ MILLER(1)                                                            MILLER(1)
          ewma       Exponentially weighted moving average over successive records
          from-first Compute differences in field(s) from first record
          ratio      Compute ratios in field(s) between successive records
+         rprod      Compute running products of field(s) between successive records
          rsum       Compute running sums of field(s) between successive records
          shift      Alias for shift_lag
          shift_lag  Include value(s) in field(s) from the previous record, if any
@@ -3316,4 +3317,4 @@ MILLER(1)                                                            MILLER(1)
 
 
 
-                                  2023-03-06                         MILLER(1)
+                                  2023-03-12                         MILLER(1)
diff --git a/man/mlr.1 b/man/mlr.1
index 1f3c54603..296057e05 100644
--- a/man/mlr.1
+++ b/man/mlr.1
@@ -2,12 +2,12 @@
 .\"     Title: mlr
 .\"    Author: [see the "AUTHOR" section]
 .\" Generator: ./mkman.rb
-.\"      Date: 2023-03-06
+.\"      Date: 2023-03-12
 .\"    Manual: \ \&
 .\"    Source: \ \&
 .\"  Language: English
 .\"
-.TH "MILLER" "1" "2023-03-06" "\ \&" "\ \&"
+.TH "MILLER" "1" "2023-03-12" "\ \&" "\ \&"
 .\" -----------------------------------------------------------------
 .\" * Portability definitions
 .\" ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
@@ -2407,6 +2407,7 @@ Options:
   ewma       Exponentially weighted moving average over successive records
   from-first Compute differences in field(s) from first record
   ratio      Compute ratios in field(s) between successive records
+  rprod      Compute running products of field(s) between successive records
   rsum       Compute running sums of field(s) between successive records
   shift      Alias for shift_lag
   shift_lag  Include value(s) in field(s) from the previous record, if any
diff --git a/test/cases/cli-help/0001/expout b/test/cases/cli-help/0001/expout
index 46edcff11..53dd46894 100644
--- a/test/cases/cli-help/0001/expout
+++ b/test/cases/cli-help/0001/expout
@@ -1110,6 +1110,7 @@ Options:
   ewma       Exponentially weighted moving average over successive records
   from-first Compute differences in field(s) from first record
   ratio      Compute ratios in field(s) between successive records
+  rprod      Compute running products of field(s) between successive records
   rsum       Compute running sums of field(s) between successive records
   shift      Alias for shift_lag
   shift_lag  Include value(s) in field(s) from the previous record, if any
diff --git a/test/cases/verb-step/0001/cmd b/test/cases/verb-step/0001/cmd
index 5c61f68d5..d918c78b4 100644
--- a/test/cases/verb-step/0001/cmd
+++ b/test/cases/verb-step/0001/cmd
@@ -1 +1 @@
-mlr --opprint step -a rsum,shift,delta,counter -f x,y test/input/abixy
+mlr --opprint step -a rsum,rprod,shift,delta,counter -f x,y test/input/abixy
diff --git a/test/cases/verb-step/0001/expout b/test/cases/verb-step/0001/expout
index a9768c81c..243ba797f 100644
--- a/test/cases/verb-step/0001/expout
+++ b/test/cases/verb-step/0001/expout
@@ -1,11 +1,11 @@
-a   b   i  x          y          x_rsum     x_shift    x_delta     x_counter y_rsum     y_shift    y_delta     y_counter
-pan pan 1  0.34679014 0.72680286 0.34679014 -          0           1         0.72680286 -          0           1
-eks pan 2  0.75867996 0.52215111 1.10547011 0.34679014 0.41188982  2         1.24895397 0.72680286 -0.20465175 2
-wye wye 3  0.20460331 0.33831853 1.31007341 0.75867996 -0.55407666 3         1.58727250 0.52215111 -0.18383258 3
-eks wye 4  0.38139939 0.13418874 1.69147281 0.20460331 0.17679609  4         1.72146124 0.33831853 -0.20412978 4
-wye pan 5  0.57328892 0.86362447 2.26476173 0.38139939 0.19188953  5         2.58508571 0.13418874 0.72943573  5
-zee pan 6  0.52712616 0.49322129 2.79188789 0.57328892 -0.04616276 6         3.07830700 0.86362447 -0.37040318 6
-eks zee 7  0.61178406 0.18788492 3.40367195 0.52712616 0.08465790  7         3.26619192 0.49322129 -0.30533637 7
-zee wye 8  0.59855401 0.97618139 4.00222596 0.61178406 -0.01323005 8         4.24237330 0.18788492 0.78829647  8
-hat wye 9  0.03144188 0.74955076 4.03366783 0.59855401 -0.56711213 9         4.99192406 0.97618139 -0.22663063 9
-pan wye 10 0.50262601 0.95261836 4.53629384 0.03144188 0.47118413  10        5.94454242 0.74955076 0.20306760  10
+a   b   i  x          y          x_rsum     x_rprod    x_shift    x_delta     x_counter y_rsum     y_rprod    y_shift    y_delta     y_counter
+pan pan 1  0.34679014 0.72680286 0.34679014 0.34679014 -          0           1         0.72680286 0.72680286 -          0           1
+eks pan 2  0.75867996 0.52215111 1.10547011 0.26310273 0.34679014 0.41188982  2         1.24895397 0.37950092 0.72680286 -0.20465175 2
+wye wye 3  0.20460331 0.33831853 1.31007341 0.05383169 0.75867996 -0.55407666 3         1.58727250 0.12839219 0.52215111 -0.18383258 3
+eks wye 4  0.38139939 0.13418874 1.69147281 0.02053137 0.20460331 0.17679609  4         1.72146124 0.01722879 0.33831853 -0.20412978 4
+wye pan 5  0.57328892 0.86362447 2.26476173 0.01177041 0.38139939 0.19188953  5         2.58508571 0.01487920 0.13418874 0.72943573  5
+zee pan 6  0.52712616 0.49322129 2.79188789 0.00620449 0.57328892 -0.04616276 6         3.07830700 0.00733874 0.86362447 -0.37040318 6
+eks zee 7  0.61178406 0.18788492 3.40367195 0.00379581 0.52712616 0.08465790  7         3.26619192 0.00137884 0.49322129 -0.30533637 7
+zee wye 8  0.59855401 0.97618139 4.00222596 0.00227200 0.61178406 -0.01323005 8         4.24237330 0.00134600 0.18788492 0.78829647  8
+hat wye 9  0.03144188 0.74955076 4.03366783 0.00007144 0.59855401 -0.56711213 9         4.99192406 0.00100889 0.97618139 -0.22663063 9
+pan wye 10 0.50262601 0.95261836 4.53629384 0.00003591 0.03144188 0.47118413  10        5.94454242 0.00096109 0.74955076 0.20306760  10
diff --git a/test/cases/verb-step/0002/cmd b/test/cases/verb-step/0002/cmd
index 60ed4285e..f20095ea5 100644
--- a/test/cases/verb-step/0002/cmd
+++ b/test/cases/verb-step/0002/cmd
@@ -1 +1 @@
-mlr --opprint step -a rsum,shift,delta,counter -f x,y -g a test/input/abixy
+mlr --opprint step -a rsum,rprod,shift,delta,counter -f x,y -g a test/input/abixy
diff --git a/test/cases/verb-step/0002/expout b/test/cases/verb-step/0002/expout
index b0dce066a..9071d71ea 100644
--- a/test/cases/verb-step/0002/expout
+++ b/test/cases/verb-step/0002/expout
@@ -1,11 +1,11 @@
-a   b   i  x          y          x_rsum     x_shift    x_delta     x_counter y_rsum     y_shift    y_delta     y_counter
-pan pan 1  0.34679014 0.72680286 0.34679014 -          0           1         0.72680286 -          0           1
-eks pan 2  0.75867996 0.52215111 0.75867996 -          0           1         0.52215111 -          0           1
-wye wye 3  0.20460331 0.33831853 0.20460331 -          0           1         0.33831853 -          0           1
-eks wye 4  0.38139939 0.13418874 1.14007936 0.75867996 -0.37728057 2         0.65633985 0.52215111 -0.38796237 2
-wye pan 5  0.57328892 0.86362447 0.77789223 0.20460331 0.36868561  2         1.20194300 0.33831853 0.52530594  2
-zee pan 6  0.52712616 0.49322129 0.52712616 -          0           1         0.49322129 -          0           1
-eks zee 7  0.61178406 0.18788492 1.75186342 0.38139939 0.23038467  3         0.84422477 0.13418874 0.05369618  3
-zee wye 8  0.59855401 0.97618139 1.12568017 0.52712616 0.07142785  2         1.46940267 0.49322129 0.48296010  2
-hat wye 9  0.03144188 0.74955076 0.03144188 -          0           1         0.74955076 -          0           1
-pan wye 10 0.50262601 0.95261836 0.84941615 0.34679014 0.15583586  2         1.67942122 0.72680286 0.22581550  2
+a   b   i  x          y          x_rsum     x_rprod    x_shift    x_delta     x_counter y_rsum     y_rprod    y_shift    y_delta     y_counter
+pan pan 1  0.34679014 0.72680286 0.34679014 0.34679014 -          0           1         0.72680286 0.72680286 -          0           1
+eks pan 2  0.75867996 0.52215111 0.75867996 0.75867996 -          0           1         0.52215111 0.52215111 -          0           1
+wye wye 3  0.20460331 0.33831853 0.20460331 0.20460331 -          0           1         0.33831853 0.33831853 -          0           1
+eks wye 4  0.38139939 0.13418874 1.14007936 0.28936008 0.75867996 -0.37728057 2         0.65633985 0.07006680 0.52215111 -0.38796237 2
+wye pan 5  0.57328892 0.86362447 0.77789223 0.11729681 0.20460331 0.36868561  2         1.20194300 0.29218016 0.33831853 0.52530594  2
+zee pan 6  0.52712616 0.49322129 0.52712616 0.52712616 -          0           1         0.49322129 0.49322129 -          0           1
+eks zee 7  0.61178406 0.18788492 1.75186342 0.17702588 0.38139939 0.23038467  3         0.84422477 0.01316450 0.13418874 0.05369618  3
+zee wye 8  0.59855401 0.97618139 1.12568017 0.31551348 0.52712616 0.07142785  2         1.46940267 0.48147344 0.49322129 0.48296010  2
+hat wye 9  0.03144188 0.74955076 0.03144188 0.03144188 -          0           1         0.74955076 0.74955076 -          0           1
+pan wye 10 0.50262601 0.95261836 0.84941615 0.17430575 0.34679014 0.15583586  2         1.67942122 0.69236575 0.72680286 0.22581550  2
diff --git a/test/cases/verb-step/0005/cmd b/test/cases/verb-step/0005/cmd
index d9ca4935b..338a8352e 100644
--- a/test/cases/verb-step/0005/cmd
+++ b/test/cases/verb-step/0005/cmd
@@ -1 +1 @@
-mlr --ojson step -a rsum,shift,delta,counter -f x,y test/input/abixy-het
+mlr --ojson step -a rsum,rprod,shift,delta,counter -f x,y test/input/abixy-het
diff --git a/test/cases/verb-step/0005/expout b/test/cases/verb-step/0005/expout
index 6b05fc756..1f7f11bf6 100644
--- a/test/cases/verb-step/0005/expout
+++ b/test/cases/verb-step/0005/expout
@@ -6,10 +6,12 @@
   "x": 0.34679014,
   "y": 0.72680286,
   "x_rsum": 0.34679014,
+  "x_rprod": 0.34679014,
   "x_shift": "",
   "x_delta": 0,
   "x_counter": 1,
   "y_rsum": 0.72680286,
+  "y_rprod": 0.72680286,
   "y_shift": "",
   "y_delta": 0,
   "y_counter": 1
@@ -21,10 +23,12 @@
   "x": 0.75867996,
   "y": 0.52215111,
   "x_rsum": 1.10547011,
+  "x_rprod": 0.26310273,
   "x_shift": 0.34679014,
   "x_delta": 0.41188982,
   "x_counter": 2,
   "y_rsum": 1.24895397,
+  "y_rprod": 0.37950092,
   "y_shift": 0.72680286,
   "y_delta": -0.20465175,
   "y_counter": 2
@@ -36,10 +40,12 @@
   "x": 0.20460331,
   "y": 0.33831853,
   "x_rsum": 1.31007341,
+  "x_rprod": 0.05383169,
   "x_shift": 0.75867996,
   "x_delta": -0.55407666,
   "x_counter": 3,
   "y_rsum": 1.58727250,
+  "y_rprod": 0.12839219,
   "y_shift": 0.52215111,
   "y_delta": -0.18383258,
   "y_counter": 3
@@ -51,10 +57,12 @@
   "x": 0.38139939,
   "y": 0.13418874,
   "x_rsum": 1.69147281,
+  "x_rprod": 0.02053137,
   "x_shift": 0.20460331,
   "x_delta": 0.17679609,
   "x_counter": 4,
   "y_rsum": 1.72146124,
+  "y_rprod": 0.01722879,
   "y_shift": 0.33831853,
   "y_delta": -0.20412978,
   "y_counter": 4
@@ -66,6 +74,7 @@
   "xxx": 0.57328892,
   "y": 0.86362447,
   "y_rsum": 2.58508571,
+  "y_rprod": 0.01487920,
   "y_shift": 0.13418874,
   "y_delta": 0.72943573,
   "y_counter": 5
@@ -77,10 +86,12 @@
   "x": 0.52712616,
   "y": 0.49322129,
   "x_rsum": 2.21859897,
+  "x_rprod": 0.01082262,
   "x_shift": "",
   "x_delta": 0,
   "x_counter": 5,
   "y_rsum": 3.07830700,
+  "y_rprod": 0.00733874,
   "y_shift": 0.86362447,
   "y_delta": -0.37040318,
   "y_counter": 6
@@ -92,10 +103,12 @@
   "x": 0.61178406,
   "y": 0.18788492,
   "x_rsum": 2.83038303,
+  "x_rprod": 0.00662111,
   "x_shift": 0.52712616,
   "x_delta": 0.08465790,
   "x_counter": 6,
   "y_rsum": 3.26619192,
+  "y_rprod": 0.00137884,
   "y_shift": 0.49322129,
   "y_delta": -0.30533637,
   "y_counter": 7
@@ -107,6 +120,7 @@
   "x": 0.59855401,
   "yyy": 0.97618139,
   "x_rsum": 3.42893704,
+  "x_rprod": 0.00396309,
   "x_shift": 0.61178406,
   "x_delta": -0.01323005,
   "x_counter": 7
@@ -118,10 +132,12 @@
   "x": 0.03144188,
   "y": 0.74955076,
   "x_rsum": 3.46037891,
+  "x_rprod": 0.00012461,
   "x_shift": 0.59855401,
   "x_delta": -0.56711213,
   "x_counter": 8,
   "y_rsum": 4.01574268,
+  "y_rprod": 0.00103351,
   "y_shift": "",
   "y_delta": 0,
   "y_counter": 8
@@ -133,10 +149,12 @@
   "x": 0.50262601,
   "y": 0.95261836,
   "x_rsum": 3.96300492,
+  "x_rprod": 0.00006263,
   "x_shift": 0.03144188,
   "x_delta": 0.47118413,
   "x_counter": 9,
   "y_rsum": 4.96836104,
+  "y_rprod": 0.00098454,
   "y_shift": 0.74955076,
   "y_delta": 0.20306760,
   "y_counter": 9