diff --git a/flang/lib/Evaluate/intrinsics.cpp b/flang/lib/Evaluate/intrinsics.cpp
--- a/flang/lib/Evaluate/intrinsics.cpp
+++ b/flang/lib/Evaluate/intrinsics.cpp
@@ -1129,9 +1129,10 @@
             d.rank == Rank::elementalOrBOZ) {
           continue;
         } else {
+          const IntrinsicDummyArgument &nextParam{dummy[j + 1]};
           messages.Say(
-              "Typeless (BOZ) not allowed for '%s=' argument"_err_en_US,
-              d.keyword);
+              "Typeless (BOZ) not allowed for either '%s=' & '%s=' arguments"_err_en_US, // C7109
+              d.keyword, nextParam.keyword);
         }
       } else {
         // NULL(), procedure, or procedure pointer
diff --git a/flang/lib/Semantics/expression.cpp b/flang/lib/Semantics/expression.cpp
--- a/flang/lib/Semantics/expression.cpp
+++ b/flang/lib/Semantics/expression.cpp
@@ -633,7 +633,8 @@
   ++p;
   auto value{BOZLiteralConstant::Read(p, base, false /*unsigned*/)};
   if (*p != '"') {
-    Say("Invalid digit ('%c') in BOZ literal '%s'"_err_en_US, *p, x.v);
+    Say("Invalid digit ('%c') in BOZ literal '%s'"_err_en_US, *p,
+        x.v); // C7107, C7108
     return std::nullopt;
   }
   if (value.overflow) {
diff --git a/flang/test/Semantics/boz-literal-constants.f90 b/flang/test/Semantics/boz-literal-constants.f90
new file mode 100644
--- /dev/null
+++ b/flang/test/Semantics/boz-literal-constants.f90
@@ -0,0 +1,79 @@
+! RUN: %S/test_errors.sh %s %t %f18
+! Confirm enforcement of constraints and restrictions in 7.7
+! C7107, C7108, C7109
+
+subroutine bozchecks
+  ! Type declaration statements
+  integer :: f, realpart = B"0101", img = B"1111", resint
+  logical :: resbit
+  complex :: rescmplx
+  real :: dbl, e
+  ! C7107
+  !ERROR: Invalid digit ('a') in BOZ literal 'b"110a"'
+  integer, parameter :: a = B"110A"
+  !ERROR: Invalid digit ('2') in BOZ literal 'b"1232"'
+  integer, parameter :: b = B"1232"
+  !ERROR: BOZ literal 'b"010101010101010101010101011111111111111111111111111111111111111111111111111111111111111111111111111111111111000000000000000000000000000000000000"' too large
+  integer, parameter :: b1 = B"010101010101010101010101011111111111111111111&
+                              &111111111111111111111111111111111111111111111&
+                              &111111111111111111000000000000000000000000000&
+                              &000000000"
+  ! C7108
+  !ERROR: Invalid digit ('8') in BOZ literal 'o"8"'
+  integer :: c = O"8"
+  !ERROR: Invalid digit ('a') in BOZ literal 'o"a"'
+  integer :: d = O"A"
+
+  ! C7109
+  !    A) can appear only in data statement
+  !    B) Argument to intrinsics listed from 16.9 below
+  !       BGE, BGT, BLE, BLT, CMPLX, DBLE, DSHIFTL,
+  !       DSHIFTR, IAND, IEOR, INT, IOR, MERGE_BITS, REAL
+
+  ! part A
+  data f / Z"AA" / ! OK
+  !ERROR: DATA statement value could not be converted to the type 'COMPLEX(4)' of the object 'rescmplx'
+  data rescmplx / B"010101" /
+  ! part B
+  resbit = BGE(B"0101", B"1111")
+  resbit = BGT(Z"0101", B"1111")
+  resbit = BLE(B"0101", B"1111")
+  resbit = BLT(B"0101", B"1111")
+
+  res = CMPLX (realpart, img, 4)
+  res = CMPLX (B"0101", B"1111", 4)
+
+  dbl = DBLE(B"1111")
+  dbl = DBLE(realpart)
+
+  !ERROR: Typeless (BOZ) not allowed for either 'i=' & 'j=' arguments
+  dbl = DSHIFTL(B"0101",B"0101",2)
+  !ERROR: Typeless (BOZ) not allowed for either 'i=' & 'j=' arguments
+  dbl = DSHIFTR(B"1010",B"1010",2)
+  dbl = DSHIFTL(B"0101",5,2) ! OK
+  dbl = DSHIFTR(B"1010",5,2) ! OK
+
+  !ERROR: Typeless (BOZ) not allowed for either 'i=' & 'j=' arguments
+  resint = IAND(B"0001", B"0011")
+  resint = IAND(B"0001", 3)
+
+  !ERROR: Typeless (BOZ) not allowed for either 'i=' & 'j=' arguments
+  resint = IEOR(B"0001", B"0011")
+  resint = IEOR(B"0001", 3)
+
+  resint = INT(B"1010")
+
+  !ERROR: Typeless (BOZ) not allowed for either 'i=' & 'j=' arguments
+  res = IOR(B"0101", B"0011")
+  res = IOR(B"0101", 3)
+
+  res = MERGE_BITS(13,3,11)
+  res = MERGE_BITS(B"1101",3,11)
+  !ERROR: Typeless (BOZ) not allowed for either 'i=' & 'j=' arguments
+  res = MERGE_BITS(B"1101",B"0011",11)
+  !ERROR: Typeless (BOZ) not allowed for either 'i=' & 'j=' arguments
+  res = MERGE_BITS(B"1101",B"0011",B"1011")
+  res = MERGE_BITS(B"1101",3,B"1011")
+
+  res = REAL(B"1101")
+end subroutine