diff --git a/components/fpspreadsheet/fpsfunc.pas b/components/fpspreadsheet/fpsfunc.pas
index 241add651..bd4692828 100644
--- a/components/fpspreadsheet/fpsfunc.pas
+++ b/components/fpspreadsheet/fpsfunc.pas
@@ -86,6 +86,21 @@ function fpsSINH        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsSQRT        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsTAN         (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsTANH        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+{ Date/time functions }
+function fpsDATE        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsDATEDIF     (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsDATEVALUE   (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsDAY         (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsHOUR        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsMINUTE      (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsMONTH       (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsNOW         (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsSECOND      (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsTIME        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsTIMEVALUE   (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsTODAY       (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsWEEKDAY     (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsYEAR        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 { Statistical functions }
 function fpsAVEDEV      (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsAVERAGE     (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
@@ -114,13 +129,23 @@ function fpsLOWER       (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsMID         (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsREPLACE     (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsRIGHT       (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsSUBSTITUTE  (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsTRIM        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 function fpsUPPER       (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+{ info functions }
+function fpsISERR       (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsISERROR     (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsISLOGICAL   (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsISNA        (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsISNONTEXT   (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsISNUMBER    (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsISTEXT      (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+function fpsVALUE       (Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 
 implementation
 
 uses
-  Math, lazutf8, StrUtils, fpsUtils;
+  Math, lazutf8, StrUtils, DateUtils, fpsUtils;
 
 type
   TBoolArray  = array of boolean;
@@ -222,6 +247,7 @@ begin
                AValue := Arg.BoolValue;
                Result := errOK;
              end;
+    atError: Result := Arg.ErrorValue;
     else     Result := errWrongType;
   end;
 end;
@@ -233,6 +259,7 @@ begin
     atNumber : ANumber := Arg.NumberValue;
     atString : if not TryStrToFloat(arg.StringValue, ANumber) then Result := errWrongType;
     atBool   : if Arg.BoolValue then ANumber := 1.0 else ANumber := 0.0;
+    atError  : Result := Arg.ErrorValue;
   end;
 end;
 
@@ -243,6 +270,7 @@ begin
                  AString := Arg.StringValue;
                  Result := errOK;
                end;
+    atError  : Result := Arg.ErrorValue;
     else       Result := errWrongType;
   end;
 end;
@@ -332,6 +360,31 @@ begin
   end;
 end;
 
+function PopDateValue(Args: TsArgumentStack; out ADate: TDate;
+  out AErrArg: TsArgument): Boolean;
+var
+  arg: TsArgument;
+begin
+  arg := Args.Pop;
+  case arg.ArgumentType of
+    atError, atBool, atEmpty:
+      begin
+        Result := false;
+        AErrArg := CreateError(errWrongType);
+      end;
+    atNumber:
+      begin
+        Result := true;
+        ADate := arg.NumberValue;
+      end;
+    atString:
+      begin
+        Result := TryStrToDate(arg.StringValue, ADate);
+        if not Result then AErrArg := CreateError(errWrongType);
+      end
+  end;
+end;
+
 {@@
   Pops floating point values from the argument stack. Is called when
   calculating rpn formulas.
@@ -435,6 +488,32 @@ begin
 end;
 
 
+function PopTimeValue(Args: TsArgumentStack; out ATime: TTime;
+  out AErrArg: TsArgument): Boolean;
+var
+  arg: TsArgument;
+begin
+  arg := Args.Pop;
+  case arg.ArgumentType of
+    atError, atBool, atEmpty:
+      begin
+        Result := false;
+        AErrArg := CreateError(errWrongType);
+      end;
+    atNumber:
+      begin
+        Result := true;
+        ATime := frac(arg.NumberValue);
+      end;
+    atString:
+      begin
+        Result := TryStrToTime(arg.StringValue, ATime);
+        if not Result then AErrArg := CreateError(errWrongType);
+      end
+  end;
+end;
+
+
 { Operations }
 
 function fpsAdd(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
@@ -759,13 +838,13 @@ begin
       base := arg_base.NumberValue;
     end;
   end;
+  arg_number := Args.Pop;
 
   if base < 0 then begin
     Result := CreateError(errOverflow);
     exit;
   end;
 
-  arg_number := Args.Pop;
   if arg_number.ArgumentType <> atNumber then begin
     Result := CreateError(errWrongType);
     exit;
@@ -872,6 +951,159 @@ begin
 end;
 
 
+{ Date/time functions }
+
+function fpsDATE(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// DATE( year, month, day )
+var
+  data: TFloatArray;
+  d: TDate;
+begin
+  if PopFloatValues(Args, 3, data, Result) then begin
+    d := EncodeDate(round(data[0]), round(data[1]), round(data[2]));
+    Result := CreateNumber(d);
+  end;
+end;
+
+function fpsDATEDIF(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+{ DATEDIF( start_date, end_date, interval )
+    start_date <= end_date !
+    interval = Y  - The number of complete years.
+             = M  - The number of complete months.
+             = D  - The number of days.
+             = MD - The difference between the days (months and years are ignored).
+             = YM - The difference between the months (days and years are ignored).
+             = YD - The difference between the days (years and dates are ignored). }
+var
+  data: TStrArray;
+  start_date, end_date: TDate;
+begin
+  if not PopStringValues(Args, 1, data, Result) then exit;
+  if not PopDateValue(Args, end_date, Result) then exit;
+  if not PopDateValue(Args, start_date, Result) then exit;
+
+  if end_date > start_date then
+    Result := CreateError(errOverflow)
+  else if data[0] = 'Y' then
+    Result := CreateNumber(YearsBetween(end_date, start_date))
+  else if data[0] = 'M' then
+    Result := CreateNumber(MonthsBetween(end_date, start_date))
+  else if data[0] = 'D' then
+    Result := CreateNumber(DaysBetween(end_date, start_date))
+  else
+    Result := CreateError(errFormulaNotSupported);
+end;
+
+function fpsDATEVALUE(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// DATEVALUE( date )   -- date can be a string or a date/time
+var
+  d: TDate;
+begin
+  if PopDateValue(Args, d, Result) then
+    Result := CreateNumber(d);
+end;
+
+function fpsDAY(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+var
+  d: TDate;
+begin
+  if PopDateValue(Args, d, Result) then
+    Result := CreateNumber(DayOf(d));
+end;
+
+function fpsHOUR(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+var
+  t: TTime;
+begin
+  if PopTimeValue(Args, t, Result) then
+    Result := CreateNumber(HourOf(t));
+end;
+
+function fpsMINUTE(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+var
+  t: TTime;
+begin
+  if PopTimeValue(Args, t, Result) then
+    Result := CreateNumber(MinuteOf(t));
+end;
+
+function fpsMONTH(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+var
+  d: TDate;
+begin
+  if PopDateValue(Args, d, Result) then
+    Result := CreateNumber(MonthOf(d));
+end;
+
+function fpsNOW(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// NOW()
+begin
+  Result := CreateNumber(now);
+end;
+
+function fpsSECOND(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+var
+  t: TTime;
+begin
+  if PopTimeValue(Args, t, Result) then
+    Result := CreateNumber(SecondOf(t));
+end;
+
+function fpsTIME(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// TIME( hour, minute, second )
+var
+  data: TFloatArray;
+  t: TTime;
+begin
+  if PopFloatValues(Args, 3, data, Result) then begin
+    t := EncodeTime(round(data[0]), round(data[1]), round(data[2]), 0);
+    Result := CreateNumber(t);
+  end;
+end;
+
+function fpsTIMEVALUE(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// TIMEVALUE( time_value )
+var
+  t: TTime;
+begin
+  if PopTimeValue(Args, t, Result) then
+    Result := CreateNumber(t);
+end;
+
+function fpsToday(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// TODAY()
+begin
+  Result := CreateNumber(Date());
+end;
+
+function fpsWEEKDAY(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+{ WEEKDAY( serial_number, [return_value]
+   return_value = 1 - Returns a number from 1 (Sunday) to 7 (Saturday).
+                      This is the default if parameter is omitted.
+                = 2 - Returns a number from 1 (Monday) to 7 (Sunday).
+                = 3 - Returns a number from 0 (Monday) to 6 (Sunday). }
+var
+  d: TDate;
+  data: TFloatArray;
+  n: Integer;
+begin
+  n := 1;
+  if NumArgs = 2 then
+    if PopFloatValues(Args, 1, data, Result) then n := round(data[0])
+      else exit;
+  if PopDateValue(Args, d, Result) then
+    Result := CreateNumber(DayOfWeek(d));
+end;
+
+function fpsYEAR(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+var
+  d: TDate;
+begin
+  if PopDateValue(Args, d, Result) then
+    Result := CreateNumber(YearOf(d));
+end;
+
+
 { Statistical functions }
 
 function fpsAVEDEV(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
@@ -901,15 +1133,19 @@ begin
 end;
 
 function fpsCOUNT(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
-{ Count non-missing arguments
+{ counts the number of cells that contain numbers as well as the number of
+  arguments that contain numbers.
   COUNT( argument1, [argument2, ... argument_n] )
 }
 var
   n, i: Integer;
+  arg: TsArgument;
 begin
   n := 0;
-  for i:=1 to NumArgs do
-    if not Args.Pop.IsMissing then inc(n);
+  for i:=1 to NumArgs do begin
+    arg := Args.Pop;
+    if (not arg.IsMissing) and (arg.ArgumentType = atNumber) then inc(n);
+  end;
   Result := CreateNumber(n);
 end;
 
@@ -1221,6 +1457,34 @@ begin
   Result := CreateString(UTF8RightStr(s, count));
 end;
 
+function fpsSUBSTITUTE(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// SUBSTITUTE( text, old_text, new_text, [nth_appearance] )
+var
+  n: Integer;
+  arg: TsArgument;
+  data: TStrArray;
+  s, s_old, s_new: String;
+begin
+  Result := CreateError(errWrongType);
+  n := -1;
+  if (NumArgs = 4) then begin
+    arg := Args.Pop;
+    if not arg.IsMissing and (arg.ArgumentType <> atNumber) then
+      exit;
+    n := round(arg.NumberValue);
+  end;
+
+  if PopStringValues(Args, 3, data, Result) then begin
+    s := data[0];
+    s_old := data[1];
+    s_new := data[2];
+    if n = -1 then
+      Result := CreateString(UTF8StringReplace(s, s_old, s_new, [rfReplaceAll]))
+    else
+      Result := CreateError(errFormulaNotSupported);
+  end;
+end;
+
 function fpsTRIM(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
 // TRIM( text )
 var
@@ -1239,4 +1503,92 @@ begin
     Result := CreateString(UTF8UpperCase(data[0]));
 end;
 
+
+{ Info functions }
+
+function fpsISERR(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// ISERR( value )
+// If value is an error value (except #N/A), this function will return TRUE.
+// Otherwise, it will return FALSE.
+var
+  arg: TsArgument;
+begin
+  arg := Args.Pop;
+  Result := CreateBool((arg.ArgumentType = atError) and (arg.ErrorValue <> errArgError));
+end;
+
+function fpsISERROR(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// ISERROR( value )
+// If value is an error value (#N/A, #VALUE!, #REF!, #DIV/0!, #NUM!, #NAME?
+// or #NULL), this function will return TRUE. Otherwise, it will return FALSE.
+var
+  arg: TsArgument;
+begin
+  arg := Args.Pop;
+  Result := CreateBool((arg.ArgumentType = atError));
+end;
+
+function fpsISLOGICAL(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// ISLOGICAL( value )
+var
+  arg: TsArgument;
+begin
+  arg := Args.Pop;
+  Result := CreateBool(arg.ArgumentType = atBool);
+end;
+
+function fpsISNA(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// ISNA( value )
+//  If value is a #N/A error value , this function will return TRUE.
+// Otherwise, it will return FALSE.
+var
+  arg: TsArgument;
+begin
+  arg := Args.Pop;
+  Result := CreateBool((arg.ArgumentType = atError) and (arg.ErrorValue = errArgError));
+end;
+
+function fpsISNONTEXT(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// ISNONTEXT( value )
+var
+  arg: TsArgument;
+begin
+  arg := Args.Pop;
+  Result := CreateBool(arg.ArgumentType <> atString);
+end;
+
+function fpsISNUMBER(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// ISNUMBER( value )
+var
+  arg: TsArgument;
+begin
+  arg := Args.Pop;
+  Result := CreateBool(arg.ArgumentType = atNumber);
+end;
+
+function fpsISTEXT(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// ISTEXT( value )
+var
+  arg: TsArgument;
+begin
+  arg := Args.Pop;
+  Result := CreateBool(arg.ArgumentType = atString);
+end;
+
+function fpsVALUE(Args: TsArgumentStack; NumArgs: Integer): TsArgument;
+// VALUE( text )
+// text is the text value to convert to a number. If text is not a number, the
+// VALUE function will return #VALUE!.
+var
+  data: TStrArray;
+  x: Double;
+begin
+  if PopStringValues(Args, 1, data, Result) then
+    if TryStrToFloat(data[0], x) then
+      Result := CreateNumber(x)
+    else
+      Result := CreateError(errWrongType);
+end;
+
+
 end.
diff --git a/components/fpspreadsheet/fpspreadsheet.pas b/components/fpspreadsheet/fpspreadsheet.pas
index dd6b64284..8a2cf7a99 100755
--- a/components/fpspreadsheet/fpspreadsheet.pas
+++ b/components/fpspreadsheet/fpspreadsheet.pas
@@ -1094,8 +1094,8 @@ type
   end;
 
 const
-  FEProps: array[TFEKind] of TFEProp = (
-  { Operands }
+  FEProps: array[TFEKind] of TFEProp = (                                        // functions marked by (*)
+  { Operands }                                                                  // are only partially supported
     (Symbol:'';          MinParams:Byte(-1); MaxParams:Byte(-1); Func:nil),     // fekCell
     (Symbol:'';          MinParams:Byte(-1); MaxParams:Byte(-1); Func:nil),     // fekCellRef
     (Symbol:'';          MinParams:Byte(-1); MaxParams:Byte(-1); Func:nil),     // fekCellRange
@@ -1149,37 +1149,37 @@ const
     (Symbol:'TAN';       MinParams:1; MaxParams:1;  Func:fpsTAN),               // fekTAN
     (Symbol:'TANH';      MinParams:1; MaxParams:1;  Func:fpsTANH),              // fekTANH,
   { date/time }
-    (Symbol:'DATE';      MinParams:3; MaxParams:3; Func:nil),   // fekDATE
-    (Symbol:'DATEDIF';   MinParams:3; MaxParams:3; Func:nil),   // fekDATEDIF
-    (Symbol:'DATEVALUE'; MinParams:1; MaxParams:1; Func:nil),   // fekDATEVALUE
-    (Symbol:'DAY';       MinParams:1; MaxParams:1; Func:nil),   // fekDAY
-    (Symbol:'HOUR';      MinParams:1; MaxParams:1; Func:nil),   // fekHOUR
-    (Symbol:'MINUTE';    MinParams:1; MaxParams:1; Func:nil),   // fekMINUTE
-    (Symbol:'MONTH';     MinParams:1; MaxParams:1; Func:nil),   // fekMONTH
-    (Symbol:'NOW';       MinParams:0; MaxParams:0; Func:nil),   // fekNOW
-    (Symbol:'SECOND';    MinParams:1; MaxParams:1; Func:nil),   // fekSECOND
-    (Symbol:'TIME';      MinParams:3; MaxParams:3; Func:nil),   // fekTIME
-    (Symbol:'TIMEVALUE'; MinParams:1; MaxParams:1; Func:nil),   // fekTIMEVALUE
-    (Symbol:'TODAY';     MinParams:0; MaxParams:0; Func:nil),   // fekTODAY
-    (Symbol:'WEEKDAY';   MinParams:1; MaxParams:2; Func:nil),   // fekWEEKDAY
-    (Symbol:'YEAR';      MinParams:1; MaxParams:1; Func:nil),   // fekYEAR
+    (Symbol:'DATE';      MinParams:3; MaxParams:3;  Func:fpsDATE),              // fekDATE
+    (Symbol:'DATEDIF';   MinParams:3; MaxParams:3;  Func:fpsDATEDIF),           // fekDATEDIF    (*)
+    (Symbol:'DATEVALUE'; MinParams:1; MaxParams:1;  Func:fpsDATEVALUE),         // fekDATEVALUE
+    (Symbol:'DAY';       MinParams:1; MaxParams:1;  Func:fpsDAY),               // fekDAY
+    (Symbol:'HOUR';      MinParams:1; MaxParams:1;  Func:fpsHOUR),              // fekHOUR
+    (Symbol:'MINUTE';    MinParams:1; MaxParams:1;  Func:fpsMINUTE),            // fekMINUTE
+    (Symbol:'MONTH';     MinParams:1; MaxParams:1;  Func:fpsMONTH),             // fekMONTH
+    (Symbol:'NOW';       MinParams:0; MaxParams:0;  Func:fpsNOW),               // fekNOW
+    (Symbol:'SECOND';    MinParams:1; MaxParams:1;  Func:fpsSECOND),            // fekSECOND
+    (Symbol:'TIME';      MinParams:3; MaxParams:3;  Func:fpsTIME),              // fekTIME
+    (Symbol:'TIMEVALUE'; MinParams:1; MaxParams:1;  Func:fpsTIMEVALUE),         // fekTIMEVALUE
+    (Symbol:'TODAY';     MinParams:0; MaxParams:0;  Func:fpsTODAY),             // fekTODAY
+    (Symbol:'WEEKDAY';   MinParams:1; MaxParams:2;  Func:fpsWEEKDAY),           // fekWEEKDAY
+    (Symbol:'YEAR';      MinParams:1; MaxParams:1;  Func:fpsYEAR),              // fekYEAR
   { statistical }
     (Symbol:'AVEDEV';    MinParams:1; MaxParams:30; Func:fpsAVEDEV),            // fekAVEDEV
     (Symbol:'AVERAGE';   MinParams:1; MaxParams:30; Func:fpsAVERAGE),           // fekAVERAGE
-    (Symbol:'BETADIST';  MinParams:3; MaxParams:5; Func:nil),   // fekBETADIST
-    (Symbol:'BETAINV';   MinParams:3; MaxParams:5; Func:nil),   // fekBETAINV
-    (Symbol:'BINOMDIST'; MinParams:4; MaxParams:4; Func:nil),   // fekBINOMDIST
-    (Symbol:'CHIDIST';   MinParams:2; MaxParams:2; Func:nil),   // fekCHIDIST
-    (Symbol:'CHIINV';    MinParams:2; MaxParams:2; Func:nil),   // fekCHIINV
+    (Symbol:'BETADIST';  MinParams:3; MaxParams:5;  Func:nil),   // fekBETADIST
+    (Symbol:'BETAINV';   MinParams:3; MaxParams:5;  Func:nil),   // fekBETAINV
+    (Symbol:'BINOMDIST'; MinParams:4; MaxParams:4;  Func:nil),   // fekBINOMDIST
+    (Symbol:'CHIDIST';   MinParams:2; MaxParams:2;  Func:nil),   // fekCHIDIST
+    (Symbol:'CHIINV';    MinParams:2; MaxParams:2;  Func:nil),   // fekCHIINV
     (Symbol:'COUNT';     MinParams:0; MaxParams:30; Func:fpsCOUNT),             // fekCOUNT
     (Symbol:'COUNTA';    MinParams:0; MaxParams:30; Func:nil),  // fekCOUNTA
-    (Symbol:'COUNTBLANK';MinParams:1; MaxParams:1; Func:nil),   // fekCOUNTBLANK
-    (Symbol:'COUNTIF';   MinParams:2; MaxParams:2; Func:nil),   // fekCOUNTIF
+    (Symbol:'COUNTBLANK';MinParams:1; MaxParams:1;  Func:nil),   // fekCOUNTBLANK
+    (Symbol:'COUNTIF';   MinParams:2; MaxParams:2;  Func:nil),   // fekCOUNTIF
     (Symbol:'MAX';       MinParams:1; MaxParams:30; Func:fpsMAX),               // fekMAX
     (Symbol:'MEDIAN';    MinParams:1; MaxParams:30; Func:nil),  // fekMEDIAN
     (Symbol:'MIN';       MinParams:1; MaxParams:30; Func:fpsMIN),               // fekMIN
-    (Symbol:'PERMUT';    MinParams:2; MaxParams:2; Func:nil),   // fekPERMUT
-    (Symbol:'POISSON';   MinParams:3; MaxParams:3; Func:nil),   // fekPOISSON
+    (Symbol:'PERMUT';    MinParams:2; MaxParams:2;  Func:nil),   // fekPERMUT
+    (Symbol:'POISSON';   MinParams:3; MaxParams:3;  Func:nil),   // fekPOISSON
     (Symbol:'PRODUCT';   MinParams:0; MaxParams:30; Func:fpsPRODUCT),           // fekPRODUCT
     (Symbol:'STDEV';     MinParams:1; MaxParams:30; Func:fpsSTDEV),             // fekSTDEV
     (Symbol:'STDEVP';    MinParams:1; MaxParams:30; Func:fpsSTDEVP),            // fekSTDEVP
@@ -1210,7 +1210,7 @@ const
     (Symbol:'PROPER';    MinParams:1; MaxParams:1; Func:nil),   // fekPROPER
     (Symbol:'REPLACE';   MinParams:4; MaxParams:4; Func:fpsREPLACE),            // fekREPLACE
     (Symbol:'RIGHT';     MinParams:1; MaxParams:2; Func:fpsRIGHT),              // fekRIGHT
-    (Symbol:'SUBSTITUTE';MinParams:3; MaxParams:4; Func:nil),   // fekSUBSTITUTE
+    (Symbol:'SUBSTITUTE';MinParams:3; MaxParams:4; Func:fpsSUBSTITUTE),         // fekSUBSTITUTE (*)
     (Symbol:'TRIM';      MinParams:1; MaxParams:1; Func:fpsTRIM),               // fekTRIM
     (Symbol:'UPPER';     MinParams:1; MaxParams:1; Func:fpsUPPER),              // fekUPPER
   {  lookup/reference }
@@ -1222,15 +1222,15 @@ const
     (Symbol:'CELL';      MinParams:1; MaxParams:2; Func:nil),   // fekCELLINFO
     (Symbol:'INFO';      MinParams:1; MaxParams:1; Func:nil),   // fekINFO
     (Symbol:'ISBLANK';   MinParams:1; MaxParams:1; Func:nil),   // fekIsBLANK
-    (Symbol:'ISERR';     MinParams:1; MaxParams:1; Func:nil),   // fekIsERR
-    (Symbol:'ISERROR';   MinParams:1; MaxParams:1; Func:nil),   // fekIsERROR
-    (Symbol:'ISLOGICAL'; MinParams:1; MaxParams:1; Func:nil),   // fekIsLOGICAL
-    (Symbol:'ISNA';      MinParams:1; MaxParams:1; Func:nil),   // fekIsNA
-    (Symbol:'ISNONTEXT'; MinParams:1; MaxParams:1; Func:nil),   // fekIsNONTEXT
-    (Symbol:'ISNUMBER';  MinParams:1; MaxParams:1; Func:nil),   // fekIsNUMBER
+    (Symbol:'ISERR';     MinParams:1; MaxParams:1; Func:fpsISERR),              // fekIsERR
+    (Symbol:'ISERROR';   MinParams:1; MaxParams:1; Func:fpsISERROR),            // fekIsERROR
+    (Symbol:'ISLOGICAL'; MinParams:1; MaxParams:1; Func:fpsISLOGICAL),          // fekIsLOGICAL
+    (Symbol:'ISNA';      MinParams:1; MaxParams:1; Func:fpsISNA),               // fekIsNA
+    (Symbol:'ISNONTEXT'; MinParams:1; MaxParams:1; Func:fpsISNONTEXT),          // fekIsNONTEXT
+    (Symbol:'ISNUMBER';  MinParams:1; MaxParams:1; Func:fpsISNUMBER),           // fekIsNUMBER
     (Symbol:'ISREF';     MinParams:1; MaxParams:1; Func:nil),   // fekIsRef
-    (Symbol:'ISTEXT';    MinParams:1; MaxParams:1; Func:nil),   // fekIsTEXT
-    (Symbol:'VALUE';     MinParams:1; MaxParams:1; Func:nil),   // fekValue
+    (Symbol:'ISTEXT';    MinParams:1; MaxParams:1; Func:fpsISTEXT),             // fekIsTEXT
+    (Symbol:'VALUE';     MinParams:1; MaxParams:1; Func:fpsVALUE),              // fekValue
   { Other operations }
     (Symbol:'SUM';       MinParams:1; MaxParams:1; Func:nil)    // fekOpSUM (Unary sum operation). Note: CANNOT be used for summing sell contents; use fekSUM}
   );
@@ -1460,14 +1460,18 @@ begin
           func := FEProps[fe.ElementKind].Func;
           if not Assigned(func) then begin
             // calculation of function not implemented
+            WriteErrorValue(ACell, errFormulaNotSupported);
             exit;
           end;
           if args.Count < fe.ParamsNum then begin
             // not enough parameters
+            WriteErrorValue(ACell, errArgError);
             exit;
           end;
           // Result of function
           val := func(args, fe.ParamsNum);
+          args.Push(val);
+          {
           // Push valid result on stack, exit in case of error
           case val.ArgumentType of
             atNumber, atString, atBool, atEmpty:
@@ -1478,6 +1482,7 @@ begin
                 exit;
               end;
           end;
+          }
       end;  // case
     end;  // for
     if args.Count = 1 then begin
@@ -1486,19 +1491,22 @@ begin
         atNumber: WriteNumber(ACell, val.NumberValue);
         atBool  : WriteBoolValue(ACell, val.BoolValue);
         atString: WriteUTF8Text(ACell, val.StringValue);
+        atError : WriteErrorValue(ACell, val.ErrorValue);
         atEmpty : WriteBlank(ACell);
       end;
     end else
+      WriteErrorValue(ACell, errArgError);
+    {
       // This case is a program error --> raise an exception
       raise Exception.CreateFmt('Incorrect argument count of the formula in cell %s', [
         GetCellString(ACell^.Row, ACell^.Col, [])
       ]);
+      }
   finally
     args.Free;
   end;
 end;
 
-
 {@@
   Converts a FPSpreadsheet cell position, which is Row, Col in numbers
   and zero based, to a textual representation which is [Col][Row],
diff --git a/components/fpspreadsheet/tests/formulatests.pas b/components/fpspreadsheet/tests/formulatests.pas
index d21c8c317..e48500d4f 100644
--- a/components/fpspreadsheet/tests/formulatests.pas
+++ b/components/fpspreadsheet/tests/formulatests.pas
@@ -6,6 +6,10 @@ unit formulatests;
   when the corresponding rpn formula is calculated. }
 {.$DEFINE ENABLE_CALC_RPN_EXCEPTIONS}
 
+{ Deactivate this define to include errors in the structure of the rpn formulas.
+  Note that Excel report a corrupted file when trying to read this file }
+{.DEFINE ENABLE_DEFECTIVE_FORMULAS }
+
 
 interface
 
@@ -143,6 +147,9 @@ var
   cell: PCell;
   sollValues: array of TsArgument;
   formula: String;
+  s: String;
+  t: TTime;
+  hr,min,sec,msec: Word;
 begin
   TempFile := GetTempFileName;
 
diff --git a/components/fpspreadsheet/tests/spreadtestgui.lpi b/components/fpspreadsheet/tests/spreadtestgui.lpi
index 86230b550..b35028661 100644
--- a/components/fpspreadsheet/tests/spreadtestgui.lpi
+++ b/components/fpspreadsheet/tests/spreadtestgui.lpi
@@ -47,6 +47,9 @@
               <UseExternalDbgSyms Value="True"/>
             </Debugging>
           </Linking>
+          <Other>
+            <CompilerPath Value="$(CompPath)"/>
+          </Other>
         </CompilerOptions>
       </Item2>
     </BuildModes>
@@ -154,6 +157,9 @@
         <OptimizationLevel Value="0"/>
       </Optimizations>
     </CodeGeneration>
+    <Other>
+      <CompilerPath Value="$(CompPath)"/>
+    </Other>
   </CompilerOptions>
   <Debugging>
     <Exceptions Count="6">
diff --git a/components/fpspreadsheet/tests/testcases_calcrpnformula.inc b/components/fpspreadsheet/tests/testcases_calcrpnformula.inc
index 6cc8eb3bb..04883ba45 100644
--- a/components/fpspreadsheet/tests/testcases_calcrpnformula.inc
+++ b/components/fpspreadsheet/tests/testcases_calcrpnformula.inc
@@ -680,6 +680,230 @@
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateNumber(tanh(0.1));
 
+
+{------------------------------------------------------------------------------}
+{                             Date/time functions                              }
+{------------------------------------------------------------------------------}
+
+  // DATE
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=DATE(2014, 7, 1)');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(2014,
+    RPNNumber(7,
+    RPNNumber(1,
+    RPNFunc(fekDATE, nil))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(EncodeDate(2014,7,1));
+
+  // DATEVALUE
+  inc(Row);
+  s := DateToStr(EncodeDate(2014, 7, 1));   // Localization of the test
+  MyWorksheet.WriteUTF8Text(Row, 0, '=DATEVALUE("'+s+'")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString(s,
+    RPNFunc(fekDATEVALUE, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(EncodeDate(2014,7,1));
+
+  // DAY  / argument number
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=DAY(DATE(2014,7,1))');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(2014,
+    RPNNumber(7,
+    RPNNumber(1,
+    RPNFunc(fekDATE,
+    RPNFunc(fekDAY, nil)))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(1);
+
+  // DAY  / argument string
+  inc(Row);
+  s := DateToStr(EncodeDate(2014, 7, 1));   // Localization of the test
+  MyWorksheet.WriteUTF8Text(Row, 0, '=DAY("'+s+'")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString(s,
+    RPNFunc(fekDAY, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(1);
+
+  // HOUR  / argument number
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=HOUR(TIME(9, 59, 20))');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(9,
+    RPNNumber(59,
+    RPNNumber(20,
+    RPNFunc(fekTIME,
+    RPNFunc(fekHOUR, nil)))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(9);
+
+  // HOUR  / argument string
+  inc(Row);
+  s := TimeToStr(EncodeTime(9, 59, 20, 0));   // Localization of the test
+  MyWorksheet.WriteUTF8Text(Row, 0, '=HOUR("'+s+'")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString(s,
+    RPNFunc(fekHOUR, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(9);
+
+  // MINUTE  / argument number
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=MINUTE(TIME(9, 59, 20))');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(9,
+    RPNNumber(59,
+    RPNNumber(20,
+    RPNFunc(fekTIME,
+    RPNFunc(fekMINUTE, nil)))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(59);
+
+  // MINUTE  / argument string
+  inc(Row);
+  s := TimeToStr(EncodeTime(9, 59, 20, 0));   // Localization of the test
+  MyWorksheet.WriteUTF8Text(Row, 0, '=MINUTE("'+s+'")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString(s,
+    RPNFunc(fekMINUTE, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(59);
+
+  // MONTH  / argument number
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=MONTH(DATE(2014,7,1))');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(2014,
+    RPNNumber(7,
+    RPNNumber(1,
+    RPNFunc(fekDATE,
+    RPNFunc(fekMONTH, nil)))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(7);
+
+  // MONTH  / argument string
+  inc(Row);
+  s := DateToStr(EncodeDate(2014, 7, 1));   // Localization of the test
+  MyWorksheet.WriteUTF8Text(Row, 0, '=MONTH("'+s+'")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString(s,
+    RPNFunc(fekMONTH, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(7);
+
+  // NOW
+  inc(Row);
+  // Make sure that, when the file is read we still have the same second
+  // Otherwise there would be a mismatch.
+  repeat
+    t := now();
+    DecodeTime(t, hr, min, sec, msec);
+  until msec < 500;
+  MyWorksheet.WriteUTF8Text(Row, 0, '=NOW()');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNFunc(fekNOW, nil)));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(t);
+
+  // SECOND  / argument number
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=SECOND(TIME(9, 59, 20))');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(9,
+    RPNNumber(59,
+    RPNNumber(20,
+    RPNFunc(fekTIME,
+    RPNFunc(fekSECOND, nil)))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(20);
+
+  // SECOND  / argument string
+  inc(Row);
+  s := TimeToStr(EncodeTime(9, 59, 20, 0));   // Localization of the test
+  MyWorksheet.WriteUTF8Text(Row, 0, '=SECOND("'+s+'")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString(s,
+    RPNFunc(fekSECOND, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(20);
+
+  // TIME
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=TIME(9, 59, 20)');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(9,
+    RPNNumber(59,
+    RPNNumber(20,
+    RPNFunc(fekTIME, nil))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(EncodeTime(9, 59, 20, 0));
+
+  // TIMEVALUE
+  inc(Row);
+  s := TimeToStr(EncodeTime(9, 59, 20, 0));  // Localization!
+  MyWorksheet.WriteUTF8Text(Row, 0, '=TIMEVALUE("'+s+'")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString(s,
+    RPNFunc(fekTIMEVALUE, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(EncodeTime(9, 59, 20, 0));
+
+  // TODAY
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=TODAY()');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNFunc(fekTODAY, nil)));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(Date());
+
+  // WEEKDAY  / argument number
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=WEEKDAY(DATE(2014,7,1))');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(2014,
+    RPNNumber(7,
+    RPNNumber(1,
+    RPNFunc(fekDATE,
+    RPNFunc(fekWEEKDAY, 1, nil)))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(DayOfWeek(EncodeDate(2014,7,1)));
+
+  // WEEKDAY  / argument string
+  inc(Row);
+  s := DateToStr(EncodeDate(2014, 7, 1));   // Localization of the test
+  MyWorksheet.WriteUTF8Text(Row, 0, '=WEEKDAY("'+s+'")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString(s,
+    RPNFunc(fekWEEKDAY, 1, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(DayOfWeek(EncodeDate(2014,7,1)));
+
+  // YEAR  / argument number
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=YEAR(DATE(2014,7,1))');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(2014,
+    RPNNumber(7,
+    RPNNumber(1,
+    RPNFunc(fekDATE,
+    RPNFunc(fekYEAR, nil)))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(2014);
+
+  // YEAR  / argument string
+  inc(Row);
+  s := DateToStr(EncodeDate(2014, 7, 1));   // Localization of the test
+  MyWorksheet.WriteUTF8Text(Row, 0, '=YEAR("'+s+'")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString(s,
+    RPNFunc(fekYEAR, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(2014);
+
+
 {------------------------------------------------------------------------------}
 {                          Statistical functions                               }
 {------------------------------------------------------------------------------}
@@ -1184,6 +1408,17 @@
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateString('d');
 
+  // SUBSTITUTE
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=SUBSTITUTE("lAzArus", "A", "a")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString('lAzArus',
+    RPNString('A',
+    RPNString('a',
+    RPNFunc(fekSUBSTITUTE, 3, nil))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateString('lazarus');
+
   // Trim
   inc(Row);
   MyWorksheet.WriteUTF8Text(Row, 0, '=TRIM("   Hallo word   ")');
@@ -1211,3 +1446,67 @@
   SetLength(sollValues, Row+1);
   sollValues[Row] := CreateString(UTF8UpperCase('Viele Grüße'));
 
+
+{------------------------------------------------------------------------------}
+{                           Information functions                              }
+{------------------------------------------------------------------------------}
+
+  // IsError
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=ISERROR(1/0)');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(1,
+    RPNNumber(0,
+    RPNFunc(fekDiv,
+    RPNFunc(fekISERROR, nil))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateBool(true);
+
+  // IsError
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=ISERROR(0/1)');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNNumber(0,
+    RPNNumber(1,
+    RPNFunc(fekDiv,
+    RPNFunc(fekISERROR, nil))))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateBool(false);
+
+  // VALUE
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=VALUE("100")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNString('100',
+    RPNFunc(fekVALUE, nil))));
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateNumber(100);
+
+{------------------------------------------------------------------------------}
+{                                Error cases                                   }
+{------------------------------------------------------------------------------}
+{$IFDEF ENABLE_DEFECTIVE_FORMULAS }
+  // Using less parameters than specified
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=IF(true,1)');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNBool(true,
+    RPNNumber(1.0,
+    RPNFunc(fekIF,3, nil)))));            // <-- we have only 2 parameters!
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateError(errArgError);
+
+  // Using more parameters than specified
+  inc(Row);
+  MyWorksheet.WriteUTF8Text(Row, 0, '=IF(true,1,"A")');
+  MyWorksheet.WriteRPNFormula(Row, 1, CreateRPNFormula(
+    RPNBool(true,
+    RPNNumber(1.0,
+    RPNString('A',
+    RPNFunc(fekIF,2, nil))))));            // <-- we have 3 parameters, not 2
+  SetLength(sollValues, Row+1);
+  sollValues[Row] := CreateError(errWrongType);
+  { The first idea was that this should report an ArgError, but in fact it is
+    a WrongType error because popping two values from the stack finds a number,
+    but a bool is expected }
+{$ENDIF}