diff --git a/documentation/new-notes/PR-655.md b/documentation/new-notes/PR-655.md
new file mode 100644
index 000000000..254ba1356
--- /dev/null
+++ b/documentation/new-notes/PR-655.md
@@ -0,0 +1,7 @@
+### Records calc, calcout and sub extended
+
+The record types calc, calcout and sub have been extended from 12 inputs
+A - L to 21 inputs A - U.
+The macro `CALCPERFORM_NARGS` reflects this change.
+The new inputs can be used in calc links and access security as well.
+The size of CALC and OCAL fields has been doubled to 160 chars.
diff --git a/modules/database/src/std/link/links.dbd.pod b/modules/database/src/std/link/links.dbd.pod
index 5247f6950..27689e321 100644
--- a/modules/database/src/std/link/links.dbd.pod
+++ b/modules/database/src/std/link/links.dbd.pod
@@ -81,11 +81,13 @@ link(calc, lnkCalcIf)
 =head3 Calculation Link C<"calc">
 
 A calculation link is an input link that can evaluate mathematical expressions
-on scalar (double-precision floating-point) values obtained from up to 12 child
+on scalar (double-precision floating-point) values obtained from up to 21 child
 input links, and returns a double-precision floating-point result. The
 expression is evaluated by the EPICS Calc engine, and the result is returned as
 the value of the link.
 
+Since UNRELEASED the number of inputs has been increased from 12 to 21.
+
 Two additional expressions may also be provided and are evaluated to determine
 whether the record owning the link should be placed in alarm state. In both
 cases the result of the main calculation is available to these expressions as
@@ -95,7 +97,7 @@ record will be placed in C<LINK/MAJOR> alarm. If not and the C<minor> expression
 evaluates to non-zero the record will be placed in C<LINK/MINOR> alarm state.
 
 A calculation link can also be an output link, with the scalar output value
-being converted to a double and provided to the expression as C<VAL>. Up to 12
+being converted to a double and provided to the expression as C<VAL>. Up to 21
 additional input links can also be read and provided to the expression as above.
 The result of the calculation is forwarded to a child output link specified in
 the link's C<out> parameter.
@@ -126,8 +128,8 @@ An optional expression that returns non-zero to raise a minor alarm.
 
 =item args
 
-A JSON list of up to 12 input arguments for the expression, which are assigned
-to the inputs C<A>, C<B>, C<C>, ... C<L>. Each input argument may be either a
+A JSON list of up to 24 input arguments for the expression, which are assigned
+to the inputs C<A>, C<B>, C<C>, ... C<U>. Each input argument may be either a
 numeric literal or an embedded JSON link inside C<{}> braces. The same input
 values are provided to the two alarm expressions as to the primary expression.
 
@@ -149,7 +151,7 @@ result should be displayed. Equivalent to the C<PREC> field of a record.
 
 =item time
 
-An optional string containing a single upper or lower-case letter C<A> ... C<L>
+An optional string containing a single upper or lower-case letter C<A> ... C<U>
 which must correspond to an input provided in the C<args> parameter. When the
 record containing such a link has C<TSEL> set to -2 (epicsTimeEventDeviceTime)
 the record's timestamp field C<TIME> will be read from the indicated input link
diff --git a/modules/database/src/std/link/lnkCalc.c b/modules/database/src/std/link/lnkCalc.c
index ed5796f8a..5f2b4888e 100644
--- a/modules/database/src/std/link/lnkCalc.c
+++ b/modules/database/src/std/link/lnkCalc.c
@@ -177,7 +177,7 @@ static jlif_result lnkCalc_string(jlink *pjlink, const char *val, size_t len)
     if (clink->pstate == ps_time) {
         char tinp;
 
-        if (len != 1 || (tinp = toupper((int) val[0])) < 'A' || tinp > 'L') {
+        if (len != 1 || (tinp = toupper((int) val[0])) < 'A' || tinp >= 'A' + CALCPERFORM_NARGS) {
             errlogPrintf("lnkCalc: Bad 'time' parameter \"%.*s\"\n", (int) len, val);
             return jlif_stop;
         }
diff --git a/modules/database/src/std/rec/calcRecord.c b/modules/database/src/std/rec/calcRecord.c
index 4467c7080..0bd7beb49 100644
--- a/modules/database/src/std/rec/calcRecord.c
+++ b/modules/database/src/std/rec/calcRecord.c
@@ -159,9 +159,9 @@ static long special(DBADDR *paddr, int after)
 #define indexof(field) calcRecord##field
 
 static long get_linkNumber(int fieldIndex) {
-    if (fieldIndex >= indexof(A) && fieldIndex <= indexof(L))
+    if (fieldIndex >= indexof(A) && fieldIndex < indexof(A) + CALCPERFORM_NARGS)
         return fieldIndex - indexof(A);
-    if (fieldIndex >= indexof(LA) && fieldIndex <= indexof(LL))
+    if (fieldIndex >= indexof(LA) && fieldIndex < indexof(LA) + CALCPERFORM_NARGS)
         return fieldIndex - indexof(LA);
     return -1;
 }
diff --git a/modules/database/src/std/rec/calcRecord.dbd.pod b/modules/database/src/std/rec/calcRecord.dbd.pod
index c8758ad53..001f34efd 100644
--- a/modules/database/src/std/rec/calcRecord.dbd.pod
+++ b/modules/database/src/std/rec/calcRecord.dbd.pod
@@ -14,6 +14,8 @@ and logical operations on values retrieved from other records. The result
 of its operations can then be accessed by another record so that it can
 then be used.
 
+Since UNRELEASED the number of inputs has been increased from 12 to 21.
+
 =head2 Parameter Fields
 
 The record-specific fields are described below, grouped by functionality.
@@ -34,9 +36,9 @@ These fields are described in L<Scan Fields|dbCommonRecord/Scan Fields>.
 
 =head3 Read Parameters
 
-The read parameters for the Calc record consist of 12 input links INPA,
-INPB, ... INPL. The fields can be database links, channel access links, or
-constants. If they are links, they must specify another record's field or a
+The read parameters for the Calc record consist of 21 input links INPA -
+INPU. The fields can be database links, channel access links, or constants.
+If they are links, they must specify another record's field or a
 channel access link. If they are constants, they will be initialized with
 the value they are configured with and can be changed via C<dbPuts>. They
 cannot be hardware addresses.
@@ -45,7 +47,7 @@ See L<Address
 Specification|https://docs.epics-controls.org/en/latest/process-database/EPICS_Process_Database_Concepts.html#address-specification>
 for information on how to specify database links.
 
-=fields INPA - INPL
+=fields INPA - INPU
 
 =head3 Expression
 
@@ -117,7 +119,7 @@ radians to degrees
 
 The expression uses the values retrieved from the INPx links as operands,
 though constants can be used as operands too. These values retrieved from
-the input links are stored in the A-L fields. The values to be used in the
+the input links are stored in the A-U fields. The values to be used in the
 expression are simply referenced by the field letter. For instance, the
 value obtained from INPA link is stored in the field A, and the value
 obtained from INPB is stored in field B. The field names can be included in
@@ -125,7 +127,7 @@ the expression which will operate on their respective values, as in A+B.
 Also, the RNDM nullary function can be included as an operand in the
 expression in order to generate a random number between 0 and 1.
 
-=fields A - L
+=fields A - U
 
 The keyword VAL returns the current contents of the VAL field (which can be
 written to by a CA put, so it might I<not> be the result from the last time
@@ -549,12 +551,12 @@ modifiable at run-time. They are used to process the record.
 The LALM field is used to implement the hysteresis factor for the alarm
 limits.
 
-The LA-LL fields are used to decide when to trigger monitors for the
+The LA-LU fields are used to decide when to trigger monitors for the
 corresponding fields. For instance, if LA does not equal the value A,
 monitors for A are triggered. The MLST and ALST fields are used in the same
 manner for the VAL field.
 
-=fields LALM, ALST, MLST, LA - LL
+=fields LALM, ALST, MLST, LA - LU
 
 =cut
 
@@ -569,7 +571,7 @@ manner for the VAL field.
 		promptgroup("30 - Action")
 		special(SPC_CALC)
 		pp(TRUE)
-		size(80)
+		size(160)
 		initial("0")
 	}
 	field(INPA,DBF_INLINK) {
@@ -632,6 +634,60 @@ manner for the VAL field.
 		promptgroup("42 - Input G-L")
 		interest(1)
 	}
+	field(INPM,DBF_INLINK) {
+		prompt("Input M")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPN,DBF_INLINK) {
+		prompt("Input N")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPO,DBF_INLINK) {
+		prompt("Input O")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPP,DBF_INLINK) {
+		prompt("Input P")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPQ,DBF_INLINK) {
+		prompt("Input Q")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPR,DBF_INLINK) {
+		prompt("Input R")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPS,DBF_INLINK) {
+		prompt("Input S")
+		special(SPC_MOD)
+		promptgroup("44 - Input S-U")
+		interest(1)
+	}
+	field(INPT,DBF_INLINK) {
+		prompt("Input T")
+		special(SPC_MOD)
+		promptgroup("44 - Input S-U")
+		interest(1)
+	}
+	field(INPU,DBF_INLINK) {
+		prompt("Input U")
+		special(SPC_MOD)
+		promptgroup("44 - Input S-U")
+		interest(1)
+	}
 	field(EGU,DBF_STRING) {
 		prompt("Engineering Units")
 		promptgroup("80 - Display")
@@ -790,6 +846,42 @@ manner for the VAL field.
 		prompt("Value of Input L")
 		pp(TRUE)
 	}
+	field(M,DBF_DOUBLE) {
+		prompt("Value of Input M")
+		pp(TRUE)
+	}
+	field(N,DBF_DOUBLE) {
+		prompt("Value of Input N")
+		pp(TRUE)
+	}
+	field(O,DBF_DOUBLE) {
+		prompt("Value of Input O")
+		pp(TRUE)
+	}
+	field(P,DBF_DOUBLE) {
+		prompt("Value of Input P")
+		pp(TRUE)
+	}
+	field(Q,DBF_DOUBLE) {
+		prompt("Value of Input Q")
+		pp(TRUE)
+	}
+	field(R,DBF_DOUBLE) {
+		prompt("Value of Input R")
+		pp(TRUE)
+	}
+	field(S,DBF_DOUBLE) {
+		prompt("Value of Input S")
+		pp(TRUE)
+	}
+	field(T,DBF_DOUBLE) {
+		prompt("Value of Input T")
+		pp(TRUE)
+	}
+	field(U,DBF_DOUBLE) {
+		prompt("Value of Input U")
+		pp(TRUE)
+	}
 	field(LA,DBF_DOUBLE) {
 		prompt("Prev Value of A")
 		special(SPC_NOMOD)
@@ -850,6 +942,51 @@ manner for the VAL field.
 		special(SPC_NOMOD)
 		interest(3)
 	}
+	field(LM,DBF_DOUBLE) {
+		prompt("Prev Value of M")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LN,DBF_DOUBLE) {
+		prompt("Prev Value of N")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LO,DBF_DOUBLE) {
+		prompt("Prev Value of O")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LP,DBF_DOUBLE) {
+		prompt("Prev Value of P")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LQ,DBF_DOUBLE) {
+		prompt("Prev Value of Q")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LR,DBF_DOUBLE) {
+		prompt("Prev Value of R")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LS,DBF_DOUBLE) {
+		prompt("Prev Value of S")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LT,DBF_DOUBLE) {
+		prompt("Prev Value of T")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LU,DBF_DOUBLE) {
+		prompt("Prev Value of U")
+		special(SPC_NOMOD)
+		interest(3)
+	}
 	field(LALM,DBF_DOUBLE) {
 		prompt("Last Value Alarmed")
 		special(SPC_NOMOD)
@@ -870,7 +1007,7 @@ manner for the VAL field.
 		prompt("Reverse Polish Calc")
 		special(SPC_NOMOD)
 		interest(4)
-		extra("char	rpcl[INFIX_TO_POSTFIX_SIZE(80)]")
+		extra("char	rpcl[INFIX_TO_POSTFIX_SIZE(160)]")
 	}
 
 =head2 Record Support
@@ -970,7 +1107,7 @@ Archive and values change monitors are invoked if ADEL and MDEL conditions
 are met.
 
 =item *
-Monitors for A-L are checked whenever other monitors are invoked.
+Monitors for A-U are checked whenever other monitors are invoked.
 
 =item *
 NSEV and NSTA are reset to 0.
diff --git a/modules/database/src/std/rec/calcoutRecord.c b/modules/database/src/std/rec/calcoutRecord.c
index 319994596..d6c2a145c 100644
--- a/modules/database/src/std/rec/calcoutRecord.c
+++ b/modules/database/src/std/rec/calcoutRecord.c
@@ -355,6 +355,15 @@ static long special(DBADDR *paddr, int after)
       case(calcoutRecordINPJ):
       case(calcoutRecordINPK):
       case(calcoutRecordINPL):
+      case(calcoutRecordINPM):
+      case(calcoutRecordINPN):
+      case(calcoutRecordINPO):
+      case(calcoutRecordINPP):
+      case(calcoutRecordINPQ):
+      case(calcoutRecordINPR):
+      case(calcoutRecordINPS):
+      case(calcoutRecordINPT):
+      case(calcoutRecordINPU):
       case(calcoutRecordOUT):
         lnkIndex = fieldIndex - calcoutRecordINPA;
         plink   = &prec->inpa + lnkIndex;
@@ -406,9 +415,9 @@ static long special(DBADDR *paddr, int after)
 #define indexof(field) calcoutRecord##field
 
 static long get_linkNumber(int fieldIndex) {
-    if (fieldIndex >= indexof(A) && fieldIndex <= indexof(L))
+    if (fieldIndex >= indexof(A) && fieldIndex < indexof(A) + CALCPERFORM_NARGS)
         return fieldIndex - indexof(A);
-    if (fieldIndex >= indexof(LA) && fieldIndex <= indexof(LL))
+    if (fieldIndex >= indexof(LA) && fieldIndex < indexof(LA) + CALCPERFORM_NARGS)
         return fieldIndex - indexof(LA);
     return -1;
 }
diff --git a/modules/database/src/std/rec/calcoutRecord.dbd.pod b/modules/database/src/std/rec/calcoutRecord.dbd.pod
index 994df0f56..82a006a5d 100644
--- a/modules/database/src/std/rec/calcoutRecord.dbd.pod
+++ b/modules/database/src/std/rec/calcoutRecord.dbd.pod
@@ -20,6 +20,8 @@ rather than the DBF_STRING fields used in the Wait record. For new
 databases, it is recommended that the Calcout record be used instead of the
 Wait record.
 
+Since UNRELEASED the number of inputs has been increased from 12 to 21.
+
 =head2 Parameter Fields
 
 The record-specific fields are described below, grouped by functionality.
@@ -57,18 +59,18 @@ These fields are listed in L<Scan Fields|dbCommonRecord/Scan Fields>.
 
 =head3 Read Parameters
 
-The read parameters for the Calcout record consists of 12 input links INPA,
-INPB, ... INPL. The fields can be database links, channel access links, or
-constants. If they are links, they must specify another record's field. If
+The read parameters for the Calcout record consists of 21 input links INPA -
+INPU. The fields can be database links, channel access links, or constants.
+If they are links, they must specify another record's field. If
 they are constants, they will be initialized with the value they are
 configured with and can be changed via C<dbPuts>. These fields cannot be
-hardware addresses. In addition, the Calcout record contains the INAV,
-INBV, ... INLV fields which indicate the status of the link fields, for
+hardware addresses. In addition, the Calcout record contains the INAV -
+INUV fields which indicate the status of the link fields, for
 example, whether or not the specified PV was found and a link to it
 established. See L<Operator Display Parameters> for an explanation of these
 fields.
 
-=fields INPA - INPL
+=fields INPA - INPU
 
 =head3 Expressions
 
@@ -146,14 +148,14 @@ angle from radians to degrees
 
 The expression can use the values retrieved from the INPx links as
 operands, though constants can be used as operands too. These values
-retrieved from the input links are stored in the A-L fields. The values to
+retrieved from the input links are stored in the A-U fields. The values to
 be used in the expression are simple references by the field letter. For
 instance, the value obtained from the INPA link is stored in field A, and
 the values obtained from the INPB link is stored in the field B. The names
 can be included in the expression will operate on their respective values,
 as in A+B.
 
-=fields A - L
+=fields A - U
 
 The keyword VAL returns the current contents of the expression's result
 field, i.e. the VAL field for the CALC expression and the OVAL field for
@@ -604,8 +606,8 @@ LOW, and LOLO fields. PREC controls the precision of the VAL field.
 
 =head4 Menu calcoutINAV
 
-The INAV-INLV fields indicate the status of the link to the PVs specified
-in the INPA-INPL fields respectively. These fields can have four possible
+The INAV-INUV fields indicate the status of the link to the PVs specified
+in the INPA-INPU fields respectively. These fields can have four possible
 values:
 
 =menu calcoutINAV
@@ -629,7 +631,7 @@ C<Constant> -- the corresponding link field is a constant.
 =back
 
 The OUTV field indicates the status of the OUT link. If has the same
-possible values as the INAV-INLV fields.
+possible values as the INAV-INUV fields.
 
 The CLCV and OLCV fields indicate the validity of the expression in the
 CALC and OCAL fields respectively. If the expression in invalid, the field
@@ -640,7 +642,7 @@ The DLYA field is set to one during the delay specified in ODLY.
 See L<Fields Common to All Record Types|dbCommonRecord/Operator Display
 Parameters> for more on the record name (NAME) and description (DESC) fields.
 
-=fields EGU, PREC, HOPR, LOPR, INAV - INLV, OUTV, CLCV, OCLV, DLYA, NAME, DESC
+=fields EGU, PREC, HOPR, LOPR, INAV - INUV, OUTV, CLCV, OCLV, DLYA, NAME, DESC
 
 =head3 Alarm Parameters
 
@@ -684,12 +686,12 @@ modifiable at run-time. They are used to process the record.
 The LALM field is used to implement the hysteresis factor for the alarm
 limits.
 
-The LA-LL fields are used to decide when to trigger monitors for the
+The LA-LU fields are used to decide when to trigger monitors for the
 corresponding fields. For instance, if LA does not equal the value for A,
 monitors for A are triggered. The MLST and ALST fields are used in the same
 manner for the VAL field.
 
-=fields LALM, ALST, MLST, LA - LL
+=fields LALM, ALST, MLST, LA - LU
 
 =cut
 
@@ -721,7 +723,7 @@ manner for the VAL field.
 		promptgroup("30 - Action")
 		special(SPC_CALC)
 		pp(TRUE)
-		size(80)
+		size(160)
 		initial("0")
 	}
 	field(CLCV,DBF_LONG) {
@@ -800,6 +802,60 @@ manner for the VAL field.
 		promptgroup("42 - Input G-L")
 		interest(1)
 	}
+	field(INPM,DBF_INLINK) {
+		prompt("Input M")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPN,DBF_INLINK) {
+		prompt("Input N")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPO,DBF_INLINK) {
+		prompt("Input O")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPP,DBF_INLINK) {
+		prompt("Input P")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPQ,DBF_INLINK) {
+		prompt("Input Q")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPR,DBF_INLINK) {
+		prompt("Input R")
+		special(SPC_MOD)
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPS,DBF_INLINK) {
+		prompt("Input S")
+		special(SPC_MOD)
+		promptgroup("44 - Input S-U")
+		interest(1)
+	}
+	field(INPT,DBF_INLINK) {
+		prompt("Input T")
+		special(SPC_MOD)
+		promptgroup("44 - Input S-U")
+		interest(1)
+	}
+	field(INPU,DBF_INLINK) {
+		prompt("Input U")
+		special(SPC_MOD)
+		promptgroup("44 - Input S-U")
+		interest(1)
+	}
 	field(OUT,DBF_OUTLINK) {
 		prompt("Output Specification")
 		special(SPC_MOD)
@@ -890,6 +946,69 @@ manner for the VAL field.
 		menu(calcoutINAV)
 		initial("1")
 	}
+	field(INMV,DBF_MENU) {
+		prompt("INPM PV Status")
+		special(SPC_NOMOD)
+		interest(1)
+		menu(calcoutINAV)
+		initial("1")
+	}
+	field(INNV,DBF_MENU) {
+		prompt("INPN PV Status")
+		special(SPC_NOMOD)
+		interest(1)
+		menu(calcoutINAV)
+		initial("1")
+	}
+	field(INOV,DBF_MENU) {
+		prompt("INPO PV Status")
+		special(SPC_NOMOD)
+		interest(1)
+		menu(calcoutINAV)
+		initial("1")
+	}
+	field(INPV,DBF_MENU) {
+		prompt("INPP PV Status")
+		special(SPC_NOMOD)
+		interest(1)
+		menu(calcoutINAV)
+		initial("1")
+	}
+	field(INQV,DBF_MENU) {
+		prompt("INPQ PV Status")
+		special(SPC_NOMOD)
+		interest(1)
+		menu(calcoutINAV)
+		initial("1")
+	}
+	field(INRV,DBF_MENU) {
+		prompt("INPR PV Status")
+		special(SPC_NOMOD)
+		interest(1)
+		menu(calcoutINAV)
+		initial("1")
+	}
+	field(INSV,DBF_MENU) {
+		prompt("INPS PV Status")
+		special(SPC_NOMOD)
+		interest(1)
+		menu(calcoutINAV)
+		initial("1")
+	}
+	field(INTV,DBF_MENU) {
+		prompt("INPT PV Status")
+		special(SPC_NOMOD)
+		interest(1)
+		menu(calcoutINAV)
+		initial("1")
+	}
+	field(INUV,DBF_MENU) {
+		prompt("INPU PV Status")
+		special(SPC_NOMOD)
+		interest(1)
+		menu(calcoutINAV)
+		initial("1")
+	}
 	field(OUTV,DBF_MENU) {
 		prompt("OUT PV Status")
 		special(SPC_NOMOD)
@@ -924,7 +1043,7 @@ manner for the VAL field.
 		promptgroup("30 - Action")
 		special(SPC_CALC)
 		pp(TRUE)
-		size(80)
+		size(160)
 		initial("0")
 	}
 	field(OCLV,DBF_LONG) {
@@ -1104,6 +1223,42 @@ manner for the VAL field.
 		prompt("Value of Input L")
 		pp(TRUE)
 	}
+	field(M,DBF_DOUBLE) {
+		prompt("Value of Input M")
+		pp(TRUE)
+	}
+	field(N,DBF_DOUBLE) {
+		prompt("Value of Input N")
+		pp(TRUE)
+	}
+	field(O,DBF_DOUBLE) {
+		prompt("Value of Input O")
+		pp(TRUE)
+	}
+	field(P,DBF_DOUBLE) {
+		prompt("Value of Input P")
+		pp(TRUE)
+	}
+	field(Q,DBF_DOUBLE) {
+		prompt("Value of Input Q")
+		pp(TRUE)
+	}
+	field(R,DBF_DOUBLE) {
+		prompt("Value of Input R")
+		pp(TRUE)
+	}
+	field(S,DBF_DOUBLE) {
+		prompt("Value of Input S")
+		pp(TRUE)
+	}
+	field(T,DBF_DOUBLE) {
+		prompt("Value of Input T")
+		pp(TRUE)
+	}
+	field(U,DBF_DOUBLE) {
+		prompt("Value of Input U")
+		pp(TRUE)
+	}
 	field(OVAL,DBF_DOUBLE) {
 		prompt("Output Value")
 		asl(ASL0)
@@ -1168,6 +1323,51 @@ manner for the VAL field.
 		special(SPC_NOMOD)
 		interest(3)
 	}
+	field(LM,DBF_DOUBLE) {
+		prompt("Prev Value of M")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LN,DBF_DOUBLE) {
+		prompt("Prev Value of N")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LO,DBF_DOUBLE) {
+		prompt("Prev Value of O")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LP,DBF_DOUBLE) {
+		prompt("Prev Value of P")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LQ,DBF_DOUBLE) {
+		prompt("Prev Value of Q")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LR,DBF_DOUBLE) {
+		prompt("Prev Value of R")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LS,DBF_DOUBLE) {
+		prompt("Prev Value of S")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LT,DBF_DOUBLE) {
+		prompt("Prev Value of T")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LU,DBF_DOUBLE) {
+		prompt("Prev Value of U")
+		special(SPC_NOMOD)
+		interest(3)
+	}
 	field(POVL,DBF_DOUBLE) {
 		prompt("Prev Value of OVAL")
 		asl(ASL0)
@@ -1192,13 +1392,13 @@ manner for the VAL field.
 		prompt("Reverse Polish Calc")
 		special(SPC_NOMOD)
 		interest(4)
-		extra("char	rpcl[INFIX_TO_POSTFIX_SIZE(80)]")
+		extra("char	rpcl[INFIX_TO_POSTFIX_SIZE(160)]")
 	}
 	field(ORPC,DBF_NOACCESS) {
 		prompt("Reverse Polish OCalc")
 		special(SPC_NOMOD)
 		interest(4)
-		extra("char	orpc[INFIX_TO_POSTFIX_SIZE(80)]")
+		extra("char	orpc[INFIX_TO_POSTFIX_SIZE(160)]")
 	}
 
 =head2 Record Support
@@ -1307,7 +1507,7 @@ Archive and value change monitors are invoked if ADEL and MDEL conditions
 are met.
 
 =item *
-Monitors for A-L are checked whenever other monitors are invoked.
+Monitors for A-U are checked whenever other monitors are invoked.
 
 =item *
 NSEV and NSTA are reset to 0
diff --git a/modules/database/src/std/rec/subRecord.c b/modules/database/src/std/rec/subRecord.c
index be274d18f..401c6a8eb 100644
--- a/modules/database/src/std/rec/subRecord.c
+++ b/modules/database/src/std/rec/subRecord.c
@@ -86,7 +86,7 @@ static long do_sub(subRecord *);
 static long fetch_values(subRecord *);
 static void monitor(subRecord *);
 
-#define INP_ARG_MAX 12
+#define INP_ARG_MAX 21
 
 static long init_record(struct dbCommon *pcommon, int pass)
 {
@@ -196,9 +196,9 @@ static long special(DBADDR *paddr, int after)
 #define indexof(field) subRecord##field
 
 static long get_linkNumber(int fieldIndex) {
-    if (fieldIndex >= indexof(A) && fieldIndex <= indexof(L))
+    if (fieldIndex >= indexof(A) && fieldIndex < indexof(A) + INP_ARG_MAX)
         return fieldIndex - indexof(A);
-    if (fieldIndex >= indexof(LA) && fieldIndex <= indexof(LL))
+    if (fieldIndex >= indexof(LA) && fieldIndex < indexof(LA) + INP_ARG_MAX)
         return fieldIndex - indexof(LA);
     return -1;
 }
diff --git a/modules/database/src/std/rec/subRecord.dbd.pod b/modules/database/src/std/rec/subRecord.dbd.pod
index 6e6edd4bb..2c7cbd291 100644
--- a/modules/database/src/std/rec/subRecord.dbd.pod
+++ b/modules/database/src/std/rec/subRecord.dbd.pod
@@ -12,6 +12,8 @@
 The subroutine record is used to call a C initialization routine and a recurring
 scan routine. There is no device support for this record.
 
+Since UNRELEASED the number of inputs has been increased from 12 to 21.
+
 =recordtype sub
 
 =cut
@@ -30,17 +32,17 @@ These fields are described in L<Scan Fields|dbCommonRecord/Scan Fields>.
 
 =head3 Read Parameters
 
-The subroutine record has twelve input links (INPA-INPL), each of which has a
-corresponding value field (A-L). These fields are used to retrieve and store
+The subroutine record has 21 input links INPA - INPU, each of which has a
+corresponding value field A - U. These fields are used to retrieve and store
 values that can be passed to the subroutine that the record calls.
 
 The input links can be either channel access or database links, or constants.
 When constants, the corresponding value field for the link is initialized with
 the constant value and the field's value can be changed at run-time via dbPuts.
-Otherwise, the values for (A-F) are fetched from the input links when the record
-is processed.
+Otherwise, the values for A - U are fetched from the input links when the
+record is processed.
 
-=fields INPA - INPL, A - L
+=fields INPA - INPU, A - U
 
 =head3 Subroutine Connection
 
@@ -115,11 +117,11 @@ processing routines or the monitors.
 VAL should be set by the subroutine. SADR holds the subroutine address and is
 set by the record processing routine.
 
-The rest of these fields--LALM, ALST, MLST, and the LA-LL fields--are used to
+The rest of these fields--LALM, ALST, MLST, and the LA-LU fields--are used to
 implement the monitors. For example, when LA is not equal to A, the value-change
 monitors are called for that field.
 
-=fields VAL, SADR, LALM, ALST, MLST, LA - LL
+=fields VAL, SADR, LALM, ALST, MLST, LA - LU
 
 =head2 Record Support
 
@@ -161,7 +163,7 @@ recGblGetPrec() >>>.
   long (*get_graphic_double)(struct dbAddr *paddr, struct dbr_grDouble *p)
 
 Sets the upper display and lower display limits for a field. If the field is
-VAL, A-L, LA-LL, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR,
+VAL, A-U, LA-LU, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR,
 else if the field has upper and lower limits defined they will be used, else the
 upper and lower maximum values for the field type will be used.
 
@@ -170,7 +172,7 @@ upper and lower maximum values for the field type will be used.
   long (*get_control_double)(struct dbAddr *paddr, struct dbr_ctrlDouble *p)
 
 Sets the upper control and the lower control limits for a field. If the field is
-VAL, A-L, LA-LL, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR,
+VAL, A-U, LA-LU, HIHI, HIGH, LOW, or LOLO, the limits are set to HOPR and LOPR,
 else if the field has upper and lower limits defined they will be used, else the
 upper and lower maximum values for the field type will be used.
 
@@ -241,7 +243,7 @@ met.
 
 =item *
 
-Monitors for A-L are invoked if value has changed.
+Monitors for A-U are invoked if value has changed.
 
 =item *
 
@@ -500,6 +502,51 @@ processing.
 		promptgroup("42 - Input G-L")
 		interest(1)
 	}
+	field(INPM,DBF_INLINK) {
+		prompt("Input M")
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPN,DBF_INLINK) {
+		prompt("Input N")
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPO,DBF_INLINK) {
+		prompt("Input O")
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPP,DBF_INLINK) {
+		prompt("Input P")
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPQ,DBF_INLINK) {
+		prompt("Input Q")
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPR,DBF_INLINK) {
+		prompt("Input R")
+		promptgroup("43 - Input M-R")
+		interest(1)
+	}
+	field(INPS,DBF_INLINK) {
+		prompt("Input S")
+		promptgroup("44 - Input S-U")
+		interest(1)
+	}
+	field(INPT,DBF_INLINK) {
+		prompt("Input T")
+		promptgroup("44 - Input S-U")
+		interest(1)
+	}
+	field(INPU,DBF_INLINK) {
+		prompt("Input U")
+		promptgroup("44 - Input S-U")
+		interest(1)
+	}
 	field(EGU,DBF_STRING) {
 		prompt("Engineering Units")
 		promptgroup("80 - Display")
@@ -655,6 +702,42 @@ processing.
 		prompt("Value of Input L")
 		pp(TRUE)
 	}
+	field(M,DBF_DOUBLE) {
+		prompt("Value of Input M")
+		pp(TRUE)
+	}
+	field(N,DBF_DOUBLE) {
+		prompt("Value of Input N")
+		pp(TRUE)
+	}
+	field(O,DBF_DOUBLE) {
+		prompt("Value of Input O")
+		pp(TRUE)
+	}
+	field(P,DBF_DOUBLE) {
+		prompt("Value of Input P")
+		pp(TRUE)
+	}
+	field(Q,DBF_DOUBLE) {
+		prompt("Value of Input Q")
+		pp(TRUE)
+	}
+	field(R,DBF_DOUBLE) {
+		prompt("Value of Input R")
+		pp(TRUE)
+	}
+	field(S,DBF_DOUBLE) {
+		prompt("Value of Input S")
+		pp(TRUE)
+	}
+	field(T,DBF_DOUBLE) {
+		prompt("Value of Input T")
+		pp(TRUE)
+	}
+	field(U,DBF_DOUBLE) {
+		prompt("Value of Input U")
+		pp(TRUE)
+	}
 	field(LA,DBF_DOUBLE) {
 		prompt("Prev Value of A")
 		special(SPC_NOMOD)
@@ -715,6 +798,51 @@ processing.
 		special(SPC_NOMOD)
 		interest(3)
 	}
+	field(LM,DBF_DOUBLE) {
+		prompt("Prev Value of M")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LN,DBF_DOUBLE) {
+		prompt("Prev Value of N")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LO,DBF_DOUBLE) {
+		prompt("Prev Value of O")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LP,DBF_DOUBLE) {
+		prompt("Prev Value of P")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LQ,DBF_DOUBLE) {
+		prompt("Prev Value of Q")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LR,DBF_DOUBLE) {
+		prompt("Prev Value of R")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LS,DBF_DOUBLE) {
+		prompt("Prev Value of S")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LT,DBF_DOUBLE) {
+		prompt("Prev Value of T")
+		special(SPC_NOMOD)
+		interest(3)
+	}
+	field(LU,DBF_DOUBLE) {
+		prompt("Prev Value of U")
+		special(SPC_NOMOD)
+		interest(3)
+	}
 	field(LALM,DBF_DOUBLE) {
 		prompt("Last Value Alarmed")
 		special(SPC_NOMOD)
diff --git a/modules/libcom/src/as/asLib_lex.l b/modules/libcom/src/as/asLib_lex.l
index df936ba34..b7f01f5c5 100644
--- a/modules/libcom/src/as/asLib_lex.l
+++ b/modules/libcom/src/as/asLib_lex.l
@@ -18,7 +18,7 @@ stringchar  [^"\n\\]
 name        [a-zA-Z0-9_\-+:.\[\]<>;]
 digit       [0-9]
 punctuation [(){},]
-link        [A-L]
+link        [A-U]
 
 %{
 static ASINPUTFUNCPTR *my_yyinput;
diff --git a/modules/libcom/src/calc/calcPerform.c b/modules/libcom/src/calc/calcPerform.c
index 81fbdc10c..8678a573d 100644
--- a/modules/libcom/src/calc/calcPerform.c
+++ b/modules/libcom/src/calc/calcPerform.c
@@ -86,6 +86,15 @@ LIBCOM_API long
         case FETCH_J:
         case FETCH_K:
         case FETCH_L:
+        case FETCH_M:
+        case FETCH_N:
+        case FETCH_O:
+        case FETCH_P:
+        case FETCH_Q:
+        case FETCH_R:
+        case FETCH_S:
+        case FETCH_T:
+        case FETCH_U:
             *++ptop = parg[op - FETCH_A];
             break;
 
@@ -101,6 +110,15 @@ LIBCOM_API long
         case STORE_J:
         case STORE_K:
         case STORE_L:
+        case STORE_M:
+        case STORE_N:
+        case STORE_O:
+        case STORE_P:
+        case STORE_Q:
+        case STORE_R:
+        case STORE_S:
+        case STORE_T:
+        case STORE_U:
             parg[op - STORE_A] = *ptop--;
             break;
 
@@ -441,6 +459,15 @@ calcArgUsage(const char *pinst, unsigned long *pinputs, unsigned long *pstores)
         case FETCH_J:
         case FETCH_K:
         case FETCH_L:
+        case FETCH_M:
+        case FETCH_N:
+        case FETCH_O:
+        case FETCH_P:
+        case FETCH_Q:
+        case FETCH_R:
+        case FETCH_S:
+        case FETCH_T:
+        case FETCH_U:
             /* Don't claim to use an arg we already stored to */
             inputs |= (1 << (op - FETCH_A)) & ~stores;
             break;
@@ -457,6 +484,15 @@ calcArgUsage(const char *pinst, unsigned long *pinputs, unsigned long *pstores)
         case STORE_J:
         case STORE_K:
         case STORE_L:
+        case STORE_M:
+        case STORE_N:
+        case STORE_O:
+        case STORE_P:
+        case STORE_Q:
+        case STORE_R:
+        case STORE_S:
+        case STORE_T:
+        case STORE_U:
             stores |= (1 << (op - STORE_A));
             break;
 
diff --git a/modules/libcom/src/calc/postfix.c b/modules/libcom/src/calc/postfix.c
index d9dce515d..2bc3e121e 100644
--- a/modules/libcom/src/calc/postfix.c
+++ b/modules/libcom/src/calc/postfix.c
@@ -117,20 +117,29 @@ static const ELEMENT operands[] = {
 {"LN",          7, 8,   0,      UNARY_OPERATOR, LOG_E},
 {"LOG",         7, 8,   0,      UNARY_OPERATOR, LOG_10},
 {"LOGE",        7, 8,   0,      UNARY_OPERATOR, LOG_E},
+{"M",           0, 0,   1,      OPERAND,        FETCH_M},
 {"MAX",         7, 8,   0,      VARARG_OPERATOR,MAX},
 {"MIN",         7, 8,   0,      VARARG_OPERATOR,MIN},
+{"N",           0, 0,   1,      OPERAND,        FETCH_N},
 {"NINT",        7, 8,   0,      UNARY_OPERATOR, NINT},
 {"NAN",         0, 0,   1,      LITERAL_OPERAND,LITERAL_DOUBLE},
 {"NOT",         7, 8,   0,      UNARY_OPERATOR, BIT_NOT},
+{"O",           0, 0,   1,      OPERAND,        FETCH_O},
+{"P",           0, 0,   1,      OPERAND,        FETCH_P},
 {"PI",          0, 0,   1,      OPERAND,        CONST_PI},
+{"Q",           0, 0,   1,      OPERAND,        FETCH_Q},
+{"R",           0, 0,   1,      OPERAND,        FETCH_R},
 {"R2D",         0, 0,   1,      OPERAND,        CONST_R2D},
 {"RNDM",        0, 0,   1,      OPERAND,        RANDOM},
+{"S",           0, 0,   1,      OPERAND,        FETCH_S},
 {"SIN",         7, 8,   0,      UNARY_OPERATOR, SIN},
 {"SINH",        7, 8,   0,      UNARY_OPERATOR, SINH},
 {"SQR",         7, 8,   0,      UNARY_OPERATOR, SQU_RT},
 {"SQRT",        7, 8,   0,      UNARY_OPERATOR, SQU_RT},
+{"T",           0, 0,   1,      OPERAND,        FETCH_T},
 {"TAN",         7, 8,   0,      UNARY_OPERATOR, TAN},
 {"TANH",        7, 8,   0,      UNARY_OPERATOR, TANH},
+{"U",           0, 0,   1,      OPERAND,        FETCH_U},
 {"VAL",         0, 0,   1,      OPERAND,        FETCH_VAL},
 {"~",           7, 8,   0,      UNARY_OPERATOR, BIT_NOT},
 };
@@ -286,7 +295,7 @@ LIBCOM_API long
 
         case STORE_OPERATOR:
             if (pout == pdest || pstacktop > stack ||
-                *--pout < FETCH_A || *pout > FETCH_L) {
+                *--pout < FETCH_A || *pout >= FETCH_A + CALCPERFORM_NARGS) {
                 *perror = CALC_ERR_BAD_ASSIGNMENT;
                 goto bad;
             }
@@ -542,9 +551,13 @@ LIBCOM_API void
         "LITERAL_DOUBLE", "LITERAL_INT", "VAL",
         "FETCH_A", "FETCH_B", "FETCH_C", "FETCH_D", "FETCH_E", "FETCH_F",
         "FETCH_G", "FETCH_H", "FETCH_I", "FETCH_J", "FETCH_K", "FETCH_L",
+        "FETCH_M", "FETCH_N", "FETCH_O", "FETCH_P", "FETCH_Q", "FETCH_R",
+        "FETCH_S", "FETCH_T", "FETCH_U",
     /* Assignment */
         "STORE_A", "STORE_B", "STORE_C", "STORE_D", "STORE_E", "STORE_F",
         "STORE_G", "STORE_H", "STORE_I", "STORE_J", "STORE_K", "STORE_L",
+        "STORE_M", "STORE_N", "STORE_O", "STORE_P", "STORE_Q", "STORE_R",
+        "STORE_S", "STORE_T", "STORE_U",
     /* Trigonometry Constants */
         "CONST_PI",
         "CONST_D2R",
diff --git a/modules/libcom/src/calc/postfix.h b/modules/libcom/src/calc/postfix.h
index 07d9d6847..1e945252c 100644
--- a/modules/libcom/src/calc/postfix.h
+++ b/modules/libcom/src/calc/postfix.h
@@ -22,8 +22,11 @@
 
 #include "libComAPI.h"
 
-/** \brief Number of input arguments to a calc expression (A-L) */
-#define CALCPERFORM_NARGS 12
+/** \brief Number of input arguments to a calc expression (A-U)
+  *
+  * Since UNRELEASED the number of inputs has been increased from 12 to 21.
+  */
+#define CALCPERFORM_NARGS 21
 /** \brief Size of the internal partial result stack */
 #define CALCPERFORM_STACK 80
 
@@ -61,7 +64,7 @@
  *
  * This is not a hard limit, just the default size for the database
  */
-#define MAX_INFIX_SIZE 100
+#define MAX_INFIX_SIZE 160
 /**
  * \brief Size of a "standard" postfix buffer.
  *
@@ -161,13 +164,13 @@ extern "C" {
  *      angle from radians to degrees.
  *
  * -# **Variables** are used to provide inputs to an expression, and are
- *  named using the single letters \c A through \c L inclusive or the
+ *  named using the single letters \c A through \c U inclusive or the
  *  keyword \c VAL which refers to the previous result of this
  *  calculation.
  *  The software that makes use of the expression evaluation code should
  *  document how the individual variables are given values.
  *  For the calc and calcout record types the input links \c INPA through
- *  \c INPL can be used to obtain values from other record fields, and \c
+ *  \c INPU can be used to obtain values from other record fields, and \c
  *  VAL refers to the the VAL field (which can be overwritten from
  *  outside the record via Channel Access or a database link).
  *
@@ -323,7 +326,7 @@ LIBCOM_API long
  * Evaluates the postfix expression against a set ot input values.
  *
  * \param parg Pointer to an array of double values for the arguments
- * \c A-L that can appear in the expression.
+ * \c A-U that can appear in the expression.
  * Note that the argument values may be modified if the expression uses
  * the assignment operator.
  * \param presult Where to put the calculated result, which may be a NaN
@@ -345,8 +348,8 @@ LIBCOM_API long
  * for either of these pointers is legal if only the other is needed.
  *
  * The least significant bit (bit 0) of the bitmap at \c *pinputs will be set
- * if the expression depends on the argument A, and so on through bit 11 for
- * the argument L. An argument that is not used until after a value has been
+ * if the expression depends on the argument A, and so on through bit 20 for
+ * the argument U. An argument that is not used until after a value has been
  * assigned to it will not be set in the pinputs bitmap, thus the bits can
  * be used to determine whether a value needs to be supplied for their
  * associated argument or not for the purposes of evaluating the expression.
diff --git a/modules/libcom/src/calc/postfixPvt.h b/modules/libcom/src/calc/postfixPvt.h
index 3e84e1fb4..23eb35b46 100644
--- a/modules/libcom/src/calc/postfixPvt.h
+++ b/modules/libcom/src/calc/postfixPvt.h
@@ -13,7 +13,7 @@
  */
 
 /* Notes:
- *  1. The FETCH_A through FETCH_L and STORE_A through STORE_L opcodes must
+ *  1. The FETCH_A through FETCH_U and STORE_A through STORE_U opcodes must
  *     be contiguous.
  *  2. The LITERAL opcodes are followed by a binary representation of their
  *     values, but these are not aligned properly.
@@ -34,9 +34,13 @@ typedef enum {
     LITERAL_DOUBLE, LITERAL_INT, FETCH_VAL,
     FETCH_A, FETCH_B, FETCH_C, FETCH_D, FETCH_E, FETCH_F,
     FETCH_G, FETCH_H, FETCH_I, FETCH_J, FETCH_K, FETCH_L,
+    FETCH_M, FETCH_N, FETCH_O, FETCH_P, FETCH_Q, FETCH_R,
+    FETCH_S, FETCH_T, FETCH_U,
     /* Assignment */
     STORE_A, STORE_B, STORE_C, STORE_D, STORE_E, STORE_F,
     STORE_G, STORE_H, STORE_I, STORE_J, STORE_K, STORE_L,
+    STORE_M, STORE_N, STORE_O, STORE_P, STORE_Q, STORE_R,
+    STORE_S, STORE_T, STORE_U,
     /* Trigonometry Constants */
     CONST_PI,
     CONST_D2R,
diff --git a/modules/libcom/test/epicsCalcTest.cpp b/modules/libcom/test/epicsCalcTest.cpp
index 4f0bfbecb..feae60570 100644
--- a/modules/libcom/test/epicsCalcTest.cpp
+++ b/modules/libcom/test/epicsCalcTest.cpp
@@ -22,7 +22,8 @@
 double doCalc(const char *expr) {
     /* Evaluate expression, return result */
     double args[CALCPERFORM_NARGS] = {
-        1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0
+        1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0,
+        13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0, 21.0
     };
     char *rpn = (char*)malloc(INFIX_TO_POSTFIX_SIZE(strlen(expr)+1));
     short err;
@@ -48,7 +49,8 @@ void testCalc(const char *expr, double expected) {
     /* Evaluate expression, test against expected result */
     bool pass = false;
     double args[CALCPERFORM_NARGS] = {
-        1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0
+        1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0,
+        13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0, 21.0
     };
     char *rpn = (char*)malloc(INFIX_TO_POSTFIX_SIZE(strlen(expr)+1));
     short err;
@@ -85,7 +87,8 @@ void testUInt32Calc(const char *expr, epicsUInt32 expected) {
     /* Evaluate expression, test against expected result */
     bool pass = false;
     double args[CALCPERFORM_NARGS] = {
-        1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0
+        1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0,
+        13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0, 21.0
     };
     char *rpn = (char*)malloc(INFIX_TO_POSTFIX_SIZE(strlen(expr)+1));
     short err;
@@ -162,18 +165,27 @@ void testBadExpr(const char *expr, short expected_err) {
 #define testExpr(expr) testCalc(#expr, expr);
 
 /* These are the argument bits for testArgs */
-#define A_A 0x001
-#define A_B 0x002
-#define A_C 0x004
-#define A_D 0x008
-#define A_E 0x010
-#define A_F 0x020
-#define A_G 0x040
-#define A_H 0x080
-#define A_I 0x100
-#define A_J 0x200
-#define A_K 0x400
-#define A_L 0x800
+#define A_A 0x000001
+#define A_B 0x000002
+#define A_C 0x000004
+#define A_D 0x000008
+#define A_E 0x000010
+#define A_F 0x000020
+#define A_G 0x000040
+#define A_H 0x000080
+#define A_I 0x000100
+#define A_J 0x000200
+#define A_K 0x000400
+#define A_L 0x000800
+#define A_M 0x001000
+#define A_N 0x002000
+#define A_O 0x004000
+#define A_P 0x008000
+#define A_Q 0x010000
+#define A_R 0x020000
+#define A_S 0x040000
+#define A_T 0x080000
+#define A_U 0x100000
 
 
 /* Macros and functions to make some expressions into valid C code */
@@ -296,9 +308,11 @@ MAIN(epicsCalcTest)
 {
     int repeat;
     const double a=1.0, b=2.0, c=3.0, d=4.0, e=5.0, f=6.0,
-                 g=7.0, h=8.0, i=9.0, j=10.0, k=11.0, l=12.0;
+                 g=7.0, h=8.0, i=9.0, j=10.0, k=11.0, l=12.0,
+                 m=13.0, n=14.0, o=15.0, p=16.0, q=17.0, r=18.0,
+                 s=19.0, t=20.0, u=21.0;
 
-    testPlan(637);
+    testPlan(687);
 
     /* LITERAL_OPERAND elements */
     testExpr(0);
@@ -335,6 +349,15 @@ MAIN(epicsCalcTest)
     testExpr(j);
     testExpr(k);
     testExpr(l);
+    testExpr(m);
+    testExpr(n);
+    testExpr(o);
+    testExpr(p);
+    testExpr(q);
+    testExpr(r);
+    testExpr(s);
+    testExpr(t);
+    testExpr(u);
     testExpr(PI);
     testExpr(D2R);
     testExpr(R2D);
@@ -832,6 +855,15 @@ MAIN(epicsCalcTest)
     testCalc("j := 0; j", 0);
     testCalc("k := 0; k", 0);
     testCalc("l := 0; l", 0);
+    testCalc("m := 0; m", 0);
+    testCalc("n := 0; n", 0);
+    testCalc("o := 0; o", 0);
+    testCalc("p := 0; p", 0);
+    testCalc("q := 0; q", 0);
+    testCalc("r := 0; r", 0);
+    testCalc("s := 0; s", 0);
+    testCalc("t := 0; t", 0);
+    testCalc("u := 0; u", 0);
 
     testCalc("a; a := 0", a);
     testCalc("b; b := 0", b);
@@ -845,6 +877,15 @@ MAIN(epicsCalcTest)
     testCalc("j; j := 0", j);
     testCalc("k; k := 0", k);
     testCalc("l; l := 0", l);
+    testCalc("m; m := 0", m);
+    testCalc("n; n := 0", n);
+    testCalc("o; o := 0", o);
+    testCalc("p; p := 0", p);
+    testCalc("q; q := 0", q);
+    testCalc("r; r := 0", r);
+    testCalc("s; s := 0", s);
+    testCalc("t; t := 0", t);
+    testCalc("u; u := 0", u);
 
     // Check relative precedences.
     testExpr(0 ? 1 : 2 | 4);                    // 0 1
@@ -921,8 +962,17 @@ MAIN(epicsCalcTest)
     testArgs("J", A_J, 0);
     testArgs("K", A_K, 0);
     testArgs("L", A_L, 0);
-    testArgs("A+B+C+D+E+F+G+H+I+J+K+L",
-        A_A|A_B|A_C|A_D|A_E|A_F|A_G|A_H|A_I|A_J|A_K|A_L, 0);
+    testArgs("M", A_M, 0);
+    testArgs("N", A_N, 0);
+    testArgs("O", A_O, 0);
+    testArgs("P", A_P, 0);
+    testArgs("Q", A_Q, 0);
+    testArgs("R", A_R, 0);
+    testArgs("S", A_S, 0);
+    testArgs("T", A_T, 0);
+    testArgs("U", A_U, 0);
+    testArgs("A+B+C+D+E+F+G+H+I+J+K+L+M+N+O+P+Q+R+S+T+U",
+        A_A|A_B|A_C|A_D|A_E|A_F|A_G|A_H|A_I|A_J|A_K|A_L|A_M|A_N|A_O|A_P|A_Q|A_R|A_S|A_T|A_U, 0);
     testArgs("0.1;A:=0", 0, A_A);
     testArgs("1.1;B:=0", 0, A_B);
     testArgs("2.1;C:=0", 0, A_C);
@@ -935,6 +985,15 @@ MAIN(epicsCalcTest)
     testArgs("9.1;J:=0", 0, A_J);
     testArgs("10.1;K:=0", 0, A_K);
     testArgs("11.1;L:=0", 0, A_L);
+    testArgs("12.1;M:=0", 0, A_M);
+    testArgs("13.1;N:=0", 0, A_N);
+    testArgs("14.1;O:=0", 0, A_O);
+    testArgs("15.1;P:=0", 0, A_P);
+    testArgs("16.1;Q:=0", 0, A_Q);
+    testArgs("17.1;R:=0", 0, A_R);
+    testArgs("18.1;S:=0", 0, A_S);
+    testArgs("19.1;T:=0", 0, A_T);
+    testArgs("20.1;U:=0", 0, A_U);
     testArgs("12.1;A:=0;B:=A;C:=B;D:=C", 0, A_A|A_B|A_C|A_D);
     testArgs("13.1;B:=A;A:=B;C:=D;D:=C", A_A|A_D, A_A|A_B|A_C|A_D);
 
@@ -955,6 +1014,11 @@ MAIN(epicsCalcTest)
     testBadExpr(":1", CALC_ERR_SYNTAX);
     testBadExpr("0,", CALC_ERR_BAD_SEPERATOR);
     testBadExpr("0)", CALC_ERR_PAREN_NOT_OPEN);
+    testBadExpr("V", CALC_ERR_SYNTAX);
+    testBadExpr("W", CALC_ERR_SYNTAX);
+    testBadExpr("X", CALC_ERR_SYNTAX);
+    testBadExpr("Y", CALC_ERR_SYNTAX);
+    testBadExpr("Z", CALC_ERR_SYNTAX);
 
     // Bit manipulations wrt bit 31 (bug lp:1514520)
     //   using integer literals