diff --git a/all.sas b/all.sas
index a7c2b12..298df2e 100644
--- a/all.sas
+++ b/all.sas
@@ -1782,6 +1782,72 @@ Usage:
 %mend;
 
 /** @endcond *//**
+  @file
+  @brief Asserts the number of observations in a dataset
+  @details Useful in the context of writing sasjs tests.  The results of the
+  test are _appended_ to the &outds. table.
+
+  Example usage:
+
+      %mp_assertdsobs(sashelp.class) %* tests if any observations are present;
+
+  <h4> SAS Macros </h4>
+  @li mf_nobs.sas
+
+
+  @param [in] inds input dataset to test for presence of observations
+  @param [in] desc= (Testing observations) The user provided test description
+  @param [in] test= (HASOBS) The test to apply.  Valid values are:
+    @li HASOBS Test is a PASS if the input dataset has any observations
+    @li EMPTY Test is a PASS if input dataset is empty
+  @param [out] outds= (work.test_results) The output dataset to contain the
+  results.  If it does not exist, it will be created, with the following format:
+  |TEST_DESCRIPTION:$256|TEST_RESULT:$4|TEST_COMMENTS:$256|
+  |---|---|---|
+  |User Provided description|PASS|Dataset &inds has XX obs|
+
+
+  @version 9.2
+  @author Allan Bowe
+
+**/
+
+%macro mp_assertdsobs(inds,
+  test=HASOBS,
+  desc=Testing observations,
+  outds=work.test_results
+)/*/STORE SOURCE*/;
+
+  %local nobs;
+  %let nobs=%mf_nobs(&inds);
+  %let test=%upcase(&test);
+
+  data;
+    length test_description $256 test_result $4 test_comments $256;
+    test_description=symget('desc');
+    test_result='FAIL';
+    test_comments="&sysmacroname: Dataset &inds has &nobs observations";
+  %if &test=HASOBS %then %do;
+    if &nobs>0 then test_result='PASS';
+  %end;
+  %else %if &test=EMPTY %then %do;
+    if &nobs=0 then test_result='PASS';
+  %end;
+  %else %do;
+    test_comments="&sysmacroname: Unsatisfied test condition - &test";
+  %end;
+  run;
+
+  %local ds;
+  %let ds=&syslast;
+
+  proc append base=&outds data=&ds;
+  run;
+
+  proc sql;
+  drop table &ds;
+
+%mend;/**
   @file
   @brief Copy any file using binary input / output streams
   @details Reads in a file byte by byte and writes it back out.  Is an
@@ -2815,6 +2881,239 @@ run;
 
 
 %mend;/**
+  @file
+  @brief Checks an input filter table for validity
+  @details Performs checks on the input table to ensure it arrives in the
+  correct format.  This is necessary to prevent code injection.  Will update
+  SYSCC to 1008 if bad records are found.
+
+  Used for dynamic filtering in [Data Controller for SAS&reg;](https://datacontroller.io).
+
+  Usage:
+
+      %mp_filtercheck(work.filter,targetds=sashelp.class,outds=work.badrecords)
+
+  The input table should have the following format:
+
+  |GROUP_LOGIC:$3|SUBGROUP_LOGIC:$3|SUBGROUP_ID:8.|VARIABLE_NM:$32|OPERATOR_NM:$10|RAW_VALUE:$32767|
+  |---|---|---|---|---|---|
+  |AND|AND|1|AGE|=|12|
+  |AND|AND|1|SEX|<=|'M'|
+  |AND|OR|2|Name|NOT IN|('Jane','Alfred')|
+  |AND|OR|2|Weight|>=|7|
+
+  Rules applied:
+
+  @li GROUP_LOGIC - only AND/OR
+  @li SUBGROUP_LOGIC - only AND/OR
+  @li SUBGROUP_ID - only integers
+  @li VARIABLE_NM - must be in the target table
+  @li OPERATOR_NM - only =/>/</<=/>=/BETWEEN/IN/NOT IN/NOT EQUAL/CONTAINS
+  @li RAW_VALUE - no unquoted values except integers, commas and spaces.
+
+  @returns The &outds table containing any bad rows, plus a REASON_CD column.
+
+  @param [in] inds The table to be checked, with the format above
+  @param [in] targetds= The target dataset against which to verify VARIABLE_NM
+  @param [out] outds= The output table, which is a copy of the &inds. table
+  plus a REASON_CD column, containing only bad records.  If bad records found,
+  the SYSCC value will be set to 1008 (general data problem).  Downstream
+  processes should check this table (and return code) before continuing.
+
+  <h4> SAS Macros </h4>
+  @li mp_abort.sas
+  @li mf_getvarlist.sas
+  @li mf_nobs.sas
+
+  <h4> Related Macros </h4>
+  @li mp_filtergenerate.sas
+
+  @version 9.3
+  @author Allan Bowe
+
+  @todo Support date / hex / name literals and exponents in RAW_VALUE field
+**/
+
+%macro mp_filtercheck(inds,targetds=,outds=work.badrecords);
+
+%mp_abort(iftrue= (&syscc ne 0)
+  ,mac=&sysmacroname
+  ,msg=%str(syscc=&syscc - on macro entry)
+)
+
+/**
+  * Sanitise the values based on valid value lists, then strip out
+  * quotes, commas, periods and spaces.
+  * Only numeric values should remain
+  */
+
+data &outds;
+  set &inds;
+  length reason_cd $32;
+
+  /* closed list checks */
+  if GROUP_LOGIC not in ('AND','OR') then do;
+    REASON_CD='GROUP_LOGIC should be either AND or OR';
+    putlog REASON_CD= GROUP_LOGIC=;
+    output;
+  end;
+  if SUBGROUP_LOGIC not in ('AND','OR') then do;
+    REASON_CD='SUBGROUP_LOGIC should be either AND or OR';
+    putlog REASON_CD= SUBGROUP_LOGIC=;
+    output;
+  end;
+  if mod(SUBGROUP_ID,1) ne 0 then do;
+    REASON_CD='SUBGROUP_ID should be integer';
+    putlog REASON_CD= SUBGROUP_ID=;
+    output;
+  end;
+  if upcase(VARIABLE_NM) not in
+  (%upcase(%mf_getvarlist(&targetds,dlm=%str(,),quote=SINGLE)))
+  then do;
+    REASON_CD="VARIABLE_NM not in &targetds";
+    putlog REASON_CD= VARIABLE_NM=;
+    output;
+  end;
+  if OPERATOR_NM not in
+  ('=','>','<','<=','>=','BETWEEN','IN','NOT IN','NOT EQUAL','CONTAINS')
+  then do;
+    REASON_CD='Invalid OPERATOR_NM';
+    putlog REASON_CD= OPERATOR_NM=;
+    output;
+  end;
+
+  /* special logic */
+  if OPERATOR_NM='BETWEEN' then raw_value1=tranwrd(raw_value,' AND ','');
+  else if OPERATOR_NM in ('IN','NOT IN') then do;
+    if substr(raw_value,1,1) ne '('
+    or substr(cats(reverse(raw_value)),1,1) ne ')'
+    then do;
+      REASON_CD='Missing brackets in RAW_VALUE';
+      putlog REASON_CD= OPERATOR_NM= raw_value= raw_value1= ;
+      output;
+    end;
+    else raw_value1=substr(raw_value,2,max(length(raw_value)-2,0));
+  end;
+  else raw_value1=raw_value;
+
+  /* remove nested literals eg '' */
+  raw_value1=tranwrd(raw_value1,"''",'');
+
+  /* now match string literals (always single quotes) */
+  raw_value2=raw_value1;
+  regex = prxparse("s/(\').*?(\')//");
+  call prxchange(regex,-1,raw_value2);
+
+  /* remove commas */
+  raw_value3=compress(raw_value2,',');
+
+
+
+
+  /* output records that contain values other than digits and spaces */
+  if notdigit(compress(raw_value3,' '))>0 then do;
+    putlog raw_value3= $hex32.;
+    REASON_CD='Invalid RAW_VALUE';
+    putlog REASON_CD= raw_value= raw_value1= raw_value2= raw_value3=;
+    output;
+  end;
+
+run;
+
+%if %mf_nobs(&outds)>0 %then %let syscc=1008;
+
+%mend;
+/**
+  @file
+  @brief Generates a filter clause from an input table, to a fileref
+  @details Uses the input table to generate an output filter clause.
+  This feature is used to create dynamic dropdowns in [Data Controller for SAS&reg](
+  https://datacontroller.io). The input table should be in the format below:
+
+  |GROUP_LOGIC:$3|SUBGROUP_LOGIC:$3|SUBGROUP_ID:8.|VARIABLE_NM:$32|OPERATOR_NM:$10|RAW_VALUE:$32767|
+  |---|---|---|---|---|---|
+  |AND|AND|1|AGE|=|12|
+  |AND|AND|1|SEX|<=|'M'|
+  |AND|OR|2|Name|NOT IN|('Jane','Alfred')|
+  |AND|OR|2|Weight|>=|7|
+
+  Note - if the above table is received from an external client, the values
+  should first be validated using the mp_filtercheck.sas macro to avoid risk
+  of SQL injection.
+
+  To generate the filter, run the following code:
+
+      data work.filtertable;
+        infile datalines4 dsd;
+        input GROUP_LOGIC:$3. SUBGROUP_LOGIC:$3. SUBGROUP_ID:8. VARIABLE_NM:$32.
+          OPERATOR_NM:$10. RAW_VALUE:$32767.;
+      datalines4;
+      AND,AND,1,AGE,=,12
+      AND,AND,1,SEX,<=,"'M'"
+      AND,OR,2,Name,NOT IN,"('Jane','Alfred')"
+      AND,OR,2,Weight,>=,7
+      ;;;;
+      run;
+
+      %mp_filtergenerate(work.filtertable,outref=myfilter)
+
+      data _null_;
+        infile myfilter;
+        input;
+        put _infile_;
+      run;
+
+  Will write the following query to the log:
+
+  > (
+  >     AGE = 12
+  >   AND
+  >     SEX <= 'M'
+  > ) AND (
+  >     Name NOT IN ('Jane','Alfred')
+  >   OR
+  >     Weight >= 7
+  > )
+
+  @param [in] inds The input table with query values
+  @param [out] outref= The output fileref to contain the filter clause.  Will
+    be created (or replaced).
+
+  <h4> Related Macros </h4>
+  @li mp_filtercheck.sas
+
+  <h4> SAS Macros </h4>
+  @li mp_abort.sas
+
+  @version 9.3
+  @author Allan Bowe
+
+**/
+
+%macro mp_filtergenerate(inds,outref=filter);
+
+%mp_abort(iftrue= (&syscc ne 0)
+  ,mac=&sysmacroname
+  ,msg=%str(syscc=&syscc - on macro entry)
+)
+
+filename &outref temp;
+
+data _null_;
+  file &outref lrecl=32800;
+  set &inds end=last;
+  by SUBGROUP_ID;
+  if _n_=1 then put '(';
+  else if first.SUBGROUP_ID then put +1 GROUP_LOGIC '(';
+  else put +2 SUBGROUP_LOGIC;
+
+  put +4 VARIABLE_NM OPERATOR_NM RAW_VALUE;
+
+  if last.SUBGROUP_ID then put ')'@;
+run;
+
+%mend;
+/**
   @file mp_getconstraints.sas
   @brief Get constraint details at column level
   @details Useful for capturing constraints before they are dropped / reapplied