diff --git a/all.sas b/all.sas
index b96943d7..a3b9ec93 100644
--- a/all.sas
+++ b/all.sas
@@ -12475,6 +12475,7 @@ run;
   @li mp_coretable.sas
   @li mp_stackdiffs.test.sas
   @li mp_storediffs.sas
+  @li mp_stripdiffs.sas
 
   @todo The current approach assumes that a variable called KEY_HASH is not on
     the base table.  This part will need to be refactored (eg using
@@ -12933,6 +12934,7 @@ select distinct tgtvar_nm into: missvars separated by ' '
   <h4> Related Macros </h4>
   @li mp_stackdiffs.sas
   @li mp_storediffs.test.sas
+  @li mp_stripdiffs.sas
 
   @version 9.2
   @author Allan Bowe
@@ -13052,7 +13054,7 @@ data &ds4;
 run;
 
 %if "&loadref"="0" %then %let loadref=%sysfunc(uuidgen());
-%if &processed_dttm=0 %then %let processed_dttm=%sysfunc(datetime());
+%if &processed_dttm=0 %then %let processed_dttm=%sysfunc(datetime(),8.6);
 %let libds=%upcase(&libds);
 
 /* join orig vals for modified & deleted */
@@ -13382,6 +13384,229 @@ run;
 
 %mend mp_streamfile;
 /**
+  @file
+  @brief Generates a stage dataset to revert diffs tracked in an audit table
+  @details A big benefit of tracking data changes in an audit table is that
+    those changes can be subsequently reverted if necessary!
+
+    This macro prepares a staging dataset containing those differences - eg for:
+
+    @li deleted rows - these are re-inserted
+    @li changed rows - differences are reverted
+    @li added rows - these are marked with `_____DELETE_THIS_RECORD_____="YES"`
+
+    These changes are NOT applied to the base table - a staging dataset is
+    simply prepared for an ETL process to action.  In Data Controller, this
+    dataset is used directly as an input to the APPROVE process (so that the
+    reversion diffs can be reviewed prior to being applied).
+
+
+  @param [in] libds Base library.dataset (will not be modified).  The library
+    must be assigned.
+  @param [in] loadref Unique identifier for the version to be reverted.  This
+    change, plus ALL SUBSEQUENT CHANGES, will be reverted in the output table.
+  @param [in] difftable The dataset containing the diffs.  Definition available
+    in mddl_dc_difftable.sas
+  @param [out] outds= (work.mp_stripdiffs) Output table containing the diffs.
+    Has the same format as the base datset, plus a
+    `_____DELETE_THIS_RECORD_____` variable.
+  @param [in] mdebug= set to 1 to enable DEBUG messages and preserve outputs
+
+  <h4> SAS Macros </h4>
+  @li mf_getuniquefileref.sas
+  @li mf_getuniquename.sas
+  @li mf_islibds.sas
+  @li mp_abort.sas
+
+  <h4> Related Macros </h4>
+  @li mddl_dc_difftable.sas
+  @li mp_stackdiffs.sas
+  @li mp_storediffs.sas
+  @li mp_stripdiffs.test.sas
+
+  @version 9.2
+  @author Allan Bowe
+**/
+/** @cond */
+
+%macro mp_stripdiffs(libds
+  ,loadref
+  ,difftable
+  ,outds=work.mp_stripdiffs
+  ,mdebug=0
+)/*/STORE SOURCE*/;
+%local dbg;
+%if &mdebug=1 %then %do;
+  %put &sysmacroname entry vars:;
+  %put _local_;
+%end;
+%else %let dbg=*;
+
+%let libds=%upcase(&libds);
+
+/* safety checks */
+%mp_abort(iftrue= (&syscc ne 0)
+  ,mac=&sysmacroname
+  ,msg=%str(SYSCC=&syscc on entry.  Clean session required!)
+)
+%let libds=%upcase(&libds);
+%mp_abort(iftrue= (%mf_islibds(&libds)=0)
+  ,mac=&sysmacroname
+  ,msg=%str(Invalid library.dataset reference - %superq(libds))
+)
+
+
+
+/* set up unique and temporary vars */
+%local ds1 ds2 ds3 ds4 ds5 fref1;
+%let fref1=%mf_getuniquefileref();
+
+/* get timestamp of the diff to be reverted */
+%local ts;
+proc sql noprint;
+select put(processed_dttm,datetime19.6) into: ts
+  from &difftable where load_ref="&loadref";
+%mp_abort(iftrue= (&sqlobs=0)
+  ,mac=&sysmacroname
+  ,msg=%str(Load ref %superq(loadref) not found!)
+)
+
+/* extract diffs for this base table from this timestamp onwards */
+%let ds1=%upcase(work.%mf_getuniquename(prefix=mpsd_diffs));
+create table &ds1 (drop=libref dsn) as
+  select * from &difftable
+  where upcase(cats(libref))="%scan(&libds,1,.)"
+  and upcase(cats(dsn))="%scan(&libds,2,.)"
+  and processed_dttm ge "&ts"dt
+  order by processed_dttm desc, key_hash, is_pk;
+
+/* extract key values only */
+%let ds2=%upcase(work.%mf_getuniquename(prefix=mpsd_pks));
+create table &ds2 as
+  select key_hash,
+    tgtvar_nm,
+    tgtvar_type,
+    coalescec(oldval_char,newval_char) as charval,
+    coalesce(oldval_num, newval_num) as numval,
+    processed_dttm
+  from &ds1
+  where is_pk=1
+  order by key_hash, processed_dttm;
+
+/* grab pk values */
+%local pk;
+data _null_;
+  set &ds2;
+  by key_hash;
+  call symputx('pk',catx(' ',symget('pk'),tgtvar_nm),'l');
+  if last.key_hash then stop;
+run;
+
+%let ds3=%upcase(work.%mf_getuniquename(prefix=mpsd_keychar));
+proc transpose data=&ds2(where=(tgtvar_type='C'))
+    out=&ds3(drop=_name_);
+  by KEY_HASH;
+  id TGTVAR_NM;
+  var charval;
+run;
+
+%let ds4=%upcase(work.%mf_getuniquename(prefix=mpsd_keynum));
+proc transpose data=&ds2(where=(tgtvar_type='N'))
+    out=&ds4(drop=_name_);
+  by KEY_HASH;
+  id TGTVAR_NM;
+  var numval;
+run;
+/* shorten the lengths */
+%mp_ds2squeeze(&ds3,outds=&ds3)
+%mp_ds2squeeze(&ds4,outds=&ds4)
+
+%let ds5=%upcase(work.%mf_getuniquename(prefix=mpsd_merged));
+data &ds5;
+  merge &ds3 &ds4;
+  by key_hash;
+  if not missing(key_hash);
+run;
+
+/* join to base table for preliminary stage DS */
+proc sql;
+create table &outds as select "No " as _____DELETE_THIS_RECORD_____,
+    b.*
+  from &ds5 a
+  inner join &libds b
+  on 1=1
+%do x=1 %to %sysfunc(countw(&pk,%str( )));
+  and a.%scan(&pk,&x,%str( ))=b.%scan(&pk,&x,%str( ))
+%end;
+;
+
+/* create SAS code to apply to stage_ds */
+data _null_;
+  set &ds1;
+  file &fref1;
+  if _n_=1 then put 'proc sql noprint;';
+  by descending processed_dttm key_hash is_pk;
+  if move_type='M' then do;
+    if first.key_hash then do;
+      put "update &outds set " @@;
+    end;
+    if IS_PK=0 then do;
+      put "  " tgtvar_nm '=' @@;
+      charval=quote(cats(oldval_char));
+      if tgtvar_type='C' then put charval @@;
+      else put oldval_num @@;
+      if not last.is_pk then put ',';
+    end;
+    else do;
+      if first.is_pk then put "  where 1=1 " @@;
+      put "  and " tgtvar_nm '=' @@;
+      charval=quote(cats(oldval_char));
+      if tgtvar_type='C' then put charval @@;
+      else put oldval_num @@;
+    end;
+  end;
+  else if move_type='A' then do;
+    if first.key_hash then do;
+      put "update &outds set _____DELETE_THIS_RECORD_____='Yes'  where 1=1 " @@;
+    end;
+    /* gating if - as only need PK now */
+    if is_pk=1;
+    put '  AND ' tgtvar_nm '=' @@;
+    charval=quote(cats(newval_char));
+    if tgtvar_type='C' then put charval @@;
+    else put newval_num @@;
+  end;
+  else if move_type='D' then do;
+    if first.key_hash then do;
+      put "insert into &outds set _____DELETE_THIS_RECORD_____='No' " @@;
+    end;
+    put "  ," tgtvar_nm '=' @@;
+    charval=quote(cats(oldval_char));
+    if tgtvar_type='C' then put charval @@;
+    else put oldval_num @@;
+  end;
+  if last.key_hash then put ';';
+run;
+
+/* apply the modification statements */
+%inc &fref1/source2;
+
+%if &mdebug=0 %then %do;
+  proc sql;
+  drop table &ds1, &ds2, &ds3, &ds4, &ds5;
+  file &fref1 clear;
+%end;
+%else %do;
+  data _null_;
+    infile &fref1;
+    input;
+    if _n_=1 then putlog "Contents of SQL adjustments";
+    putlog _infile_;
+  run;
+%end;
+
+%mend mp_stripdiffs;
+/** @endcond *//**
   @file
   @brief Runs arbitrary code for a specified amount of time
   @details Executes a series of procs and data steps to enable performance
@@ -17973,10 +18198,11 @@ run;
 
   @param [in] user= the metadata user to return groups for.  Leave blank for all
     groups.
-  @param [in] repo= the metadata repository that contains the user/group
-    information
-  @param [in] mDebug= set to 1 to show debug messages in the log
-  @param [out] outds= the dataset to create that contains the list of groups
+  @param [in] repo= (foundation) the metadata repository that contains the
+    user/group information
+  @param [in] mDebug= (0) set to 1 to show debug messages in the log
+  @param [out] outds= (work.mm_getgroups) The dataset to create that contains
+    the list of groups
 
   @returns outds  dataset containing all groups in a column named "metagroup"
     - groupuri
diff --git a/base/mp_stackdiffs.sas b/base/mp_stackdiffs.sas
index ce167009..65aa4df2 100644
--- a/base/mp_stackdiffs.sas
+++ b/base/mp_stackdiffs.sas
@@ -197,6 +197,7 @@
   @li mp_coretable.sas
   @li mp_stackdiffs.test.sas
   @li mp_storediffs.sas
+  @li mp_stripdiffs.sas
 
   @todo The current approach assumes that a variable called KEY_HASH is not on
     the base table.  This part will need to be refactored (eg using
diff --git a/base/mp_storediffs.sas b/base/mp_storediffs.sas
index f185b0cc..452c5797 100644
--- a/base/mp_storediffs.sas
+++ b/base/mp_storediffs.sas
@@ -64,6 +64,7 @@
   <h4> Related Macros </h4>
   @li mp_stackdiffs.sas
   @li mp_storediffs.test.sas
+  @li mp_stripdiffs.sas
 
   @version 9.2
   @author Allan Bowe
@@ -183,7 +184,7 @@ data &ds4;
 run;
 
 %if "&loadref"="0" %then %let loadref=%sysfunc(uuidgen());
-%if &processed_dttm=0 %then %let processed_dttm=%sysfunc(datetime());
+%if &processed_dttm=0 %then %let processed_dttm=%sysfunc(datetime(),8.6);
 %let libds=%upcase(&libds);
 
 /* join orig vals for modified & deleted */
diff --git a/base/mp_stripdiffs.sas b/base/mp_stripdiffs.sas
new file mode 100644
index 00000000..50028187
--- /dev/null
+++ b/base/mp_stripdiffs.sas
@@ -0,0 +1,224 @@
+/**
+  @file
+  @brief Generates a stage dataset to revert diffs tracked in an audit table
+  @details A big benefit of tracking data changes in an audit table is that
+    those changes can be subsequently reverted if necessary!
+
+    This macro prepares a staging dataset containing those differences - eg for:
+
+    @li deleted rows - these are re-inserted
+    @li changed rows - differences are reverted
+    @li added rows - these are marked with `_____DELETE_THIS_RECORD_____="YES"`
+
+    These changes are NOT applied to the base table - a staging dataset is
+    simply prepared for an ETL process to action.  In Data Controller, this
+    dataset is used directly as an input to the APPROVE process (so that the
+    reversion diffs can be reviewed prior to being applied).
+
+
+  @param [in] libds Base library.dataset (will not be modified).  The library
+    must be assigned.
+  @param [in] loadref Unique identifier for the version to be reverted.  This
+    change, plus ALL SUBSEQUENT CHANGES, will be reverted in the output table.
+  @param [in] difftable The dataset containing the diffs.  Definition available
+    in mddl_dc_difftable.sas
+  @param [out] outds= (work.mp_stripdiffs) Output table containing the diffs.
+    Has the same format as the base datset, plus a
+    `_____DELETE_THIS_RECORD_____` variable.
+  @param [in] mdebug= set to 1 to enable DEBUG messages and preserve outputs
+
+  <h4> SAS Macros </h4>
+  @li mf_getuniquefileref.sas
+  @li mf_getuniquename.sas
+  @li mf_islibds.sas
+  @li mp_abort.sas
+
+  <h4> Related Macros </h4>
+  @li mddl_dc_difftable.sas
+  @li mp_stackdiffs.sas
+  @li mp_storediffs.sas
+  @li mp_stripdiffs.test.sas
+
+  @version 9.2
+  @author Allan Bowe
+**/
+/** @cond */
+
+%macro mp_stripdiffs(libds
+  ,loadref
+  ,difftable
+  ,outds=work.mp_stripdiffs
+  ,mdebug=0
+)/*/STORE SOURCE*/;
+%local dbg;
+%if &mdebug=1 %then %do;
+  %put &sysmacroname entry vars:;
+  %put _local_;
+%end;
+%else %let dbg=*;
+
+%let libds=%upcase(&libds);
+
+/* safety checks */
+%mp_abort(iftrue= (&syscc ne 0)
+  ,mac=&sysmacroname
+  ,msg=%str(SYSCC=&syscc on entry.  Clean session required!)
+)
+%let libds=%upcase(&libds);
+%mp_abort(iftrue= (%mf_islibds(&libds)=0)
+  ,mac=&sysmacroname
+  ,msg=%str(Invalid library.dataset reference - %superq(libds))
+)
+
+
+
+/* set up unique and temporary vars */
+%local ds1 ds2 ds3 ds4 ds5 fref1;
+%let fref1=%mf_getuniquefileref();
+
+/* get timestamp of the diff to be reverted */
+%local ts;
+proc sql noprint;
+select put(processed_dttm,datetime19.6) into: ts
+  from &difftable where load_ref="&loadref";
+%mp_abort(iftrue= (&sqlobs=0)
+  ,mac=&sysmacroname
+  ,msg=%str(Load ref %superq(loadref) not found!)
+)
+
+/* extract diffs for this base table from this timestamp onwards */
+%let ds1=%upcase(work.%mf_getuniquename(prefix=mpsd_diffs));
+create table &ds1 (drop=libref dsn) as
+  select * from &difftable
+  where upcase(cats(libref))="%scan(&libds,1,.)"
+  and upcase(cats(dsn))="%scan(&libds,2,.)"
+  and processed_dttm ge "&ts"dt
+  order by processed_dttm desc, key_hash, is_pk;
+
+/* extract key values only */
+%let ds2=%upcase(work.%mf_getuniquename(prefix=mpsd_pks));
+create table &ds2 as
+  select key_hash,
+    tgtvar_nm,
+    tgtvar_type,
+    coalescec(oldval_char,newval_char) as charval,
+    coalesce(oldval_num, newval_num) as numval,
+    processed_dttm
+  from &ds1
+  where is_pk=1
+  order by key_hash, processed_dttm;
+
+/* grab pk values */
+%local pk;
+data _null_;
+  set &ds2;
+  by key_hash;
+  call symputx('pk',catx(' ',symget('pk'),tgtvar_nm),'l');
+  if last.key_hash then stop;
+run;
+
+%let ds3=%upcase(work.%mf_getuniquename(prefix=mpsd_keychar));
+proc transpose data=&ds2(where=(tgtvar_type='C'))
+    out=&ds3(drop=_name_);
+  by KEY_HASH;
+  id TGTVAR_NM;
+  var charval;
+run;
+
+%let ds4=%upcase(work.%mf_getuniquename(prefix=mpsd_keynum));
+proc transpose data=&ds2(where=(tgtvar_type='N'))
+    out=&ds4(drop=_name_);
+  by KEY_HASH;
+  id TGTVAR_NM;
+  var numval;
+run;
+/* shorten the lengths */
+%mp_ds2squeeze(&ds3,outds=&ds3)
+%mp_ds2squeeze(&ds4,outds=&ds4)
+
+%let ds5=%upcase(work.%mf_getuniquename(prefix=mpsd_merged));
+data &ds5;
+  merge &ds3 &ds4;
+  by key_hash;
+  if not missing(key_hash);
+run;
+
+/* join to base table for preliminary stage DS */
+proc sql;
+create table &outds as select "No " as _____DELETE_THIS_RECORD_____,
+    b.*
+  from &ds5 a
+  inner join &libds b
+  on 1=1
+%do x=1 %to %sysfunc(countw(&pk,%str( )));
+  and a.%scan(&pk,&x,%str( ))=b.%scan(&pk,&x,%str( ))
+%end;
+;
+
+/* create SAS code to apply to stage_ds */
+data _null_;
+  set &ds1;
+  file &fref1;
+  if _n_=1 then put 'proc sql noprint;';
+  by descending processed_dttm key_hash is_pk;
+  if move_type='M' then do;
+    if first.key_hash then do;
+      put "update &outds set " @@;
+    end;
+    if IS_PK=0 then do;
+      put "  " tgtvar_nm '=' @@;
+      charval=quote(cats(oldval_char));
+      if tgtvar_type='C' then put charval @@;
+      else put oldval_num @@;
+      if not last.is_pk then put ',';
+    end;
+    else do;
+      if first.is_pk then put "  where 1=1 " @@;
+      put "  and " tgtvar_nm '=' @@;
+      charval=quote(cats(oldval_char));
+      if tgtvar_type='C' then put charval @@;
+      else put oldval_num @@;
+    end;
+  end;
+  else if move_type='A' then do;
+    if first.key_hash then do;
+      put "update &outds set _____DELETE_THIS_RECORD_____='Yes'  where 1=1 " @@;
+    end;
+    /* gating if - as only need PK now */
+    if is_pk=1;
+    put '  AND ' tgtvar_nm '=' @@;
+    charval=quote(cats(newval_char));
+    if tgtvar_type='C' then put charval @@;
+    else put newval_num @@;
+  end;
+  else if move_type='D' then do;
+    if first.key_hash then do;
+      put "insert into &outds set _____DELETE_THIS_RECORD_____='No' " @@;
+    end;
+    put "  ," tgtvar_nm '=' @@;
+    charval=quote(cats(oldval_char));
+    if tgtvar_type='C' then put charval @@;
+    else put oldval_num @@;
+  end;
+  if last.key_hash then put ';';
+run;
+
+/* apply the modification statements */
+%inc &fref1/source2;
+
+%if &mdebug=0 %then %do;
+  proc sql;
+  drop table &ds1, &ds2, &ds3, &ds4, &ds5;
+  file &fref1 clear;
+%end;
+%else %do;
+  data _null_;
+    infile &fref1;
+    input;
+    if _n_=1 then putlog "Contents of SQL adjustments";
+    putlog _infile_;
+  run;
+%end;
+
+%mend mp_stripdiffs;
+/** @endcond */
\ No newline at end of file
diff --git a/meta/mm_getgroups.sas b/meta/mm_getgroups.sas
index d63104e6..f61a1e3b 100755
--- a/meta/mm_getgroups.sas
+++ b/meta/mm_getgroups.sas
@@ -11,10 +11,11 @@
 
   @param [in] user= the metadata user to return groups for.  Leave blank for all
     groups.
-  @param [in] repo= the metadata repository that contains the user/group
-    information
-  @param [in] mDebug= set to 1 to show debug messages in the log
-  @param [out] outds= the dataset to create that contains the list of groups
+  @param [in] repo= (foundation) the metadata repository that contains the
+    user/group information
+  @param [in] mDebug= (0) set to 1 to show debug messages in the log
+  @param [out] outds= (work.mm_getgroups) The dataset to create that contains
+    the list of groups
 
   @returns outds  dataset containing all groups in a column named "metagroup"
     - groupuri
diff --git a/tests/base/mp_stripdiffs.test.sas b/tests/base/mp_stripdiffs.test.sas
new file mode 100644
index 00000000..e0ccd677
--- /dev/null
+++ b/tests/base/mp_stripdiffs.test.sas
@@ -0,0 +1,106 @@
+/**
+  @file
+  @brief Testing mp_stripdiffs.sas macro
+  @details
+
+  <h4> SAS Macros </h4>
+  @li mp_assert.sas
+  @li mp_assertscope.sas
+  @li mp_ds2md.sas
+  @li mp_stripdiffs.sas
+
+**/
+
+/* make an adjustable base dataset */
+/* use a composite key also (name weight) */
+libname libby (work);
+data libby.class;
+  set sashelp.class;
+run;
+
+/* first, store some diffs */
+data work.orig work.deleted work.changed work.appended;
+  set libby.class;
+  if _n_=1 then do;
+    call symputx('delname',name);
+    output work.orig work.deleted;
+  end;
+  else if _n_=2 then do;
+    output work.orig;
+    call symputx('modname',name);
+    call symputx('modval',age);
+    age=99;
+    output work.changed;
+  end;
+  else do;
+    name='Newbie';
+    output work.appended;
+    stop;
+  end;
+run;
+%mp_storediffs(libby.class,work.orig,NAME WEIGHT
+  ,delds=work.deleted
+  ,modds=work.changed
+  ,appds=work.appended
+  ,outds=work.audit
+  ,loadref=UPLOAD1
+  ,mdebug=0
+)
+%mp_ds2md(work.audit)
+%mp_assert(
+  iftrue=(&syscc=0),
+  desc=Checking preparation case,
+  outds=work.test_results
+)
+
+/* apply the changes */
+proc sql;
+delete from libby.class where name in ("&delname","&modname");
+proc append base=libby.class data=work.appended;
+proc append base=libby.class data=work.changed;
+run;
+
+/* now, prepare the revert dataset */
+%mp_assertscope(SNAPSHOT)
+%mp_stripdiffs(libby.class
+  ,UPLOAD1
+  ,work.audit
+  ,outds=work.mp_stripdiffs
+  ,mdebug=1
+)
+%mp_ds2md(work.mp_stripdiffs)
+%mp_assertscope(COMPARE)
+
+%mp_assert(
+  iftrue=(&syscc=0),
+  desc=Checking error condition,
+  outds=work.test_results
+)
+
+%let delpass=0;
+%let modpass=0;
+%let addpass=0;
+data _null_;
+  set work.mp_stripdiffs;
+  if upcase(_____DELETE_THIS_RECORD_____)='NO' and name="&delname"
+  then call symputx('delpass',1);
+  if name="&modname" and age=&modval then call symputx('modpass',1);
+  if upcase(_____DELETE_THIS_RECORD_____)='YES' and name="Newbie"
+  then call symputx('addpass',1);
+run;
+
+%mp_assert(
+  iftrue=(&delpass=1),
+  desc=Ensuring deleted record is back in the dataset,
+  outds=work.test_results
+)
+%mp_assert(
+  iftrue=(&modpass=1),
+  desc=Ensuring modified record now has old value,
+  outds=work.test_results
+)
+%mp_assert(
+  iftrue=(&addpass=1),
+  desc=Ensuring added record is now marked for deletion,
+  outds=work.test_results
+)
\ No newline at end of file