diff --git a/bit.go b/bit.go
new file mode 100644
index 0000000..6ff0402
--- /dev/null
+++ b/bit.go
@@ -0,0 +1,8 @@
+package rfc2234
+
+// IsBit returns true if the value of 'r' matches 'BIT' as defined in IETF RFC-2234:
+//
+//	BIT =  "0" / "1"
+func IsBit(r rune) bool {
+	return ('0' == r || '1' == r)
+}
diff --git a/bit_test.go b/bit_test.go
new file mode 100644
index 0000000..7337d9c
--- /dev/null
+++ b/bit_test.go
@@ -0,0 +1,57 @@
+package rfc2234_test
+
+import (
+	"testing"
+
+	"sourcecode.social/reiver/go-rfc2234"
+)
+
+func TestIsBit(t *testing.T) {
+
+	tests := []struct{
+		Rune rune
+		Expected bool
+	}{
+	}
+
+	for r:=rune(0); r < '0'; r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: false,
+		})
+	}
+	for r:='0'; r <= '1'; r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: true,
+		})
+	}
+	for r:='1'+1; r <= rune(1024); r++ {
+		tests = append(tests, struct{
+			Rune rune
+			Expected bool
+		}{
+			Rune: r,
+			Expected: false,
+		})
+	}
+
+	for testNumber, test := range tests {
+		actual := rfc2234.IsBit(test.Rune)
+		expected := test.Expected
+
+		if expected != actual {
+			t.Errorf("For test #%d, the actual value for rfc2234.IsBit() is not what was expected.", testNumber)
+			t.Logf("EXPECTED: %t", expected)
+			t.Logf("ACTUAL:   %t", actual)
+			t.Logf("RUNE: (%U) %q", test.Rune, string(test.Rune))
+			continue
+		}
+	}
+}