diff --git a/pkg/corset/parser.go b/pkg/corset/parser.go
index 80f9e63..9944c92 100644
--- a/pkg/corset/parser.go
+++ b/pkg/corset/parser.go
@@ -379,8 +379,22 @@ func (p *Parser) parseColumnDeclarationAttributes(attrs []sexp.SExp) (Type, bool
 		}
 		//
 		switch symbol.Value {
-		case ":display", ":opcode":
+		case ":display":
 			// skip these for now, as they are only relevant to the inspector.
+			if i+1 == len(attrs) {
+				return nil, false, p.translator.SyntaxError(ith, "incomplete display definition")
+			} else if attrs[i+1].AsSymbol() == nil {
+				return nil, false, p.translator.SyntaxError(ith, "malformed display definition")
+			}
+			// Check what display attribute we have
+			switch attrs[i+1].AsSymbol().String(false) {
+			case ":dec", ":hex", ":bytes", ":opcode":
+				// all good
+				i = i + 1
+			default:
+				// not good
+				return nil, false, p.translator.SyntaxError(ith, "unknown display definition")
+			}
 		case ":array":
 			if array, err = p.parseArrayDimension(attrs[i+1]); err != nil {
 				return nil, false, err
diff --git a/pkg/test/invalid_corset_test.go b/pkg/test/invalid_corset_test.go
index bc94688..b5f3de7 100644
--- a/pkg/test/invalid_corset_test.go
+++ b/pkg/test/invalid_corset_test.go
@@ -283,6 +283,30 @@ func Test_Invalid_Type_08(t *testing.T) {
 	CheckInvalid(t, "type_invalid_08")
 }
 
+func Test_Invalid_Type_09(t *testing.T) {
+	CheckInvalid(t, "type_invalid_09")
+}
+
+func Test_Invalid_Type_10(t *testing.T) {
+	CheckInvalid(t, "type_invalid_10")
+}
+
+func Test_Invalid_Type_11(t *testing.T) {
+	CheckInvalid(t, "type_invalid_11")
+}
+
+func Test_Invalid_Type_12(t *testing.T) {
+	CheckInvalid(t, "type_invalid_12")
+}
+
+func Test_Invalid_Type_13(t *testing.T) {
+	CheckInvalid(t, "type_invalid_13")
+}
+
+func Test_Invalid_Type_14(t *testing.T) {
+	CheckInvalid(t, "type_invalid_14")
+}
+
 // ===================================================================
 // Range Constraints
 // ===================================================================
diff --git a/pkg/test/valid_corset_test.go b/pkg/test/valid_corset_test.go
index f24d494..adcf72a 100644
--- a/pkg/test/valid_corset_test.go
+++ b/pkg/test/valid_corset_test.go
@@ -408,6 +408,14 @@ func Test_Type_08(t *testing.T) {
 	Check(t, false, "type_08")
 }
 
+func Test_Type_09(t *testing.T) {
+	Check(t, false, "type_09")
+}
+
+func Test_Type_10(t *testing.T) {
+	Check(t, false, "type_10")
+}
+
 // ===================================================================
 // Range Constraints
 // ===================================================================
@@ -794,11 +802,10 @@ func TestSlow_Euc(t *testing.T) {
 	Check(t, true, "euc")
 }
 
-/*
-	 func TestSlow_Oob(t *testing.T) {
-		Check(t, true, "oob")
-	}
-*/
+func TestSlow_Oob(t *testing.T) {
+	Check(t, true, "oob")
+}
+
 func TestSlow_Stp(t *testing.T) {
 	Check(t, true, "stp")
 }
diff --git a/testdata/oob.lisp b/testdata/oob.lisp
index 0ec0b74..a839679 100644
--- a/testdata/oob.lisp
+++ b/testdata/oob.lisp
@@ -36,6 +36,45 @@
   (OUTGOING_DATA :i128 :array [4])
   (OUTGOING_RES_LO :i128))
 
+(defconst
+  ;; Stop and Arithmetic Operations
+  EVM_INST_ADD                              0x01
+  EVM_INST_DIV                              0x04
+  EVM_INST_MOD                              0x06
+  ;; Comparison & Bitwise Logic Operations
+  EVM_INST_LT                               0x10
+  EVM_INST_GT                               0x11
+  EVM_INST_EQ                               0x14
+  EVM_INST_ISZERO                           0x15
+  ;;
+  MAX_CODE_SIZE                             24576
+  EIP2681_MAX_NONCE                         18446744073709551615               ;; = 2^64 - 1
+  ;;
+  GAS_CONST_G_CALL_STIPEND                  2300
+  ;;
+  OOB_INST_JUMP                             0x56
+  OOB_INST_JUMPI                            0x57
+  OOB_INST_RDC                              0x3E
+  OOB_INST_CDL                              0x35
+  OOB_INST_XCALL                            0xCC
+  OOB_INST_CALL                             0xCA
+  OOB_INST_CREATE                           0xCE
+  OOB_INST_SSTORE                           0x55
+  OOB_INST_DEPLOYMENT                       0xF3
+  OOB_INST_ECRECOVER                        0xFF01
+  OOB_INST_SHA2                             0xFF02
+  OOB_INST_RIPEMD                           0xFF03
+  OOB_INST_IDENTITY                         0xFF04
+  OOB_INST_ECADD                            0xFF06
+  OOB_INST_ECMUL                            0xFF07
+  OOB_INST_ECPAIRING                        0xFF08
+  OOB_INST_BLAKE_CDS                        0xFA09
+  OOB_INST_BLAKE_PARAMS                     0xFB09
+  OOB_INST_MODEXP_CDS                       0xFA05
+  OOB_INST_MODEXP_XBS                       0xFB05
+  OOB_INST_MODEXP_LEAD                      0xFC05
+  OOB_INST_MODEXP_PRICING                   0xFD05
+  OOB_INST_MODEXP_EXTRACT                   0xFE05)
 
 (module oob)
 
diff --git a/testdata/type_09.accepts b/testdata/type_09.accepts
index aa9e59f..51fab06 100644
--- a/testdata/type_09.accepts
+++ b/testdata/type_09.accepts
@@ -24,4 +24,4 @@
 { "BIT": [0,1], "X": [1,0] }
 { "BIT": [0,1], "X": [2,0] }
 ;;
-{ "BIT": [1,1], "X": [1,1] }
+{ "BIT": [1,1], "X": [0,0] }
diff --git a/testdata/type_09.lisp b/testdata/type_09.lisp
index da202f4..9db0b6a 100644
--- a/testdata/type_09.lisp
+++ b/testdata/type_09.lisp
@@ -1,2 +1,2 @@
-(defcolumns (X :i1@bool@prove) (Y :i4@loob))
-(defconstraint c1 () (if X Y))
+(defcolumns (BIT :i1@bool@prove) (X :i4@loob))
+(defconstraint c1 () (if BIT X))
diff --git a/testdata/type_10.accepts b/testdata/type_10.accepts
new file mode 100644
index 0000000..3fde5de
--- /dev/null
+++ b/testdata/type_10.accepts
@@ -0,0 +1,6 @@
+{ "A": [], "B": [], "C": [], "D": [] }
+{ "A": [0], "B": [0], "C": [0], "D": [0] }
+{ "A": [1], "B": [0], "C": [0], "D": [0] }
+{ "A": [0], "B": [1], "C": [0], "D": [0] }
+{ "A": [0], "B": [0], "C": [1], "D": [0] }
+{ "A": [0], "B": [0], "C": [0], "D": [1] }
diff --git a/testdata/type_10.lisp b/testdata/type_10.lisp
new file mode 100644
index 0000000..c78d217
--- /dev/null
+++ b/testdata/type_10.lisp
@@ -0,0 +1,5 @@
+(defcolumns
+  (A :display :dec)
+  (B :display :hex)
+  (C :display :bytes)
+  (D :display :opcode))
diff --git a/testdata/type_invalid_09.lisp b/testdata/type_invalid_09.lisp
index 68e5d41..04c1c03 100644
--- a/testdata/type_invalid_09.lisp
+++ b/testdata/type_invalid_09.lisp
@@ -1,4 +1,4 @@
-;;error:2:1-2:blah
+;;error:6:26-27:invalid condition (neither loobean nor boolean)
 (defcolumns (X :i1) (Y :i1) (A :i4@loob) (B :i4@loob))
 (definterleaved Z (X Y))
 (definterleaved C (A B))
diff --git a/testdata/type_invalid_10.lisp b/testdata/type_invalid_10.lisp
index 688e509..95126f4 100644
--- a/testdata/type_invalid_10.lisp
+++ b/testdata/type_invalid_10.lisp
@@ -1,4 +1,4 @@
-;;error:2:1-2:blah
+;;error:6:26-27:invalid condition (neither loobean nor boolean)
 (defcolumns (X :i1@loob) (Y :i1) (A :i4@loob) (B :i4@loob))
 (definterleaved Z (X Y))
 (definterleaved C (A B))
diff --git a/testdata/type_invalid_11.lisp b/testdata/type_invalid_11.lisp
index 0045b57..d39bea5 100644
--- a/testdata/type_invalid_11.lisp
+++ b/testdata/type_invalid_11.lisp
@@ -1,4 +1,4 @@
-;;error:2:1-2:blah
+;;error:6:26-27:invalid condition (neither loobean nor boolean)
 (defcolumns (X :i1) (Y :i1@loob) (A :i4@loob) (B :i4@loob))
 (definterleaved Z (X Y))
 (definterleaved C (A B))
diff --git a/testdata/type_invalid_12.lisp b/testdata/type_invalid_12.lisp
index 1fa5e1c..ecebd09 100644
--- a/testdata/type_invalid_12.lisp
+++ b/testdata/type_invalid_12.lisp
@@ -1,4 +1,4 @@
-;;error:2:1-2:blah
+;;error:6:26-27:invalid condition (neither loobean nor boolean)
 (defcolumns (X :i1@bool) (Y :i1) (A :i4@loob) (B :i4@loob))
 (definterleaved Z (X Y))
 (definterleaved C (A B))
diff --git a/testdata/type_invalid_13.lisp b/testdata/type_invalid_13.lisp
index 7cd1415..0f2c87d 100644
--- a/testdata/type_invalid_13.lisp
+++ b/testdata/type_invalid_13.lisp
@@ -1,4 +1,4 @@
-;;error:2:1-2:blah
+;;error:6:26-27:invalid condition (neither loobean nor boolean)
 (defcolumns (X :i1) (Y :i1@bool) (A :i4@loob) (B :i4@loob))
 (definterleaved Z (X Y))
 (definterleaved C (A B))
diff --git a/testdata/type_invalid_14.lisp b/testdata/type_invalid_14.lisp
new file mode 100644
index 0000000..e9bc0dd
--- /dev/null
+++ b/testdata/type_invalid_14.lisp
@@ -0,0 +1,4 @@
+;;error:3:16-24:incomplete display definition
+;;error:4:16-24:unknown display definition
+(defcolumns (X :display))
+(defcolumns (Y :display :int))