Clarify decimal datatype constraints and simplify validation

schema/json/metaschema-datatypes.json

@@ -42,9 +42,8 @@
       "pattern": "^-?P([0-9]+D(T(([0-9]+H([0-9]+M)?(([0-9]+|[0-9]+(\\.[0-9]+)?)S)?)|([0-9]+M(([0-9]+|[0-9]+(\\.[0-9]+)?)S)?)|([0-9]+|[0-9]+(\\.[0-9]+)?)S))?)|T(([0-9]+H([0-9]+M)?(([0-9]+|[0-9]+(\\.[0-9]+)?)S)?)|([0-9]+M(([0-9]+|[0-9]+(\\.[0-9]+)?)S)?)|([0-9]+|[0-9]+(\\.[0-9]+)?)S)$"
     },
     "DecimalDatatype": {
-      "description": "A real number expressed using a whole and optional fractional part separated by a period.",
-      "type": "number",
-      "pattern": "^(\\+|-)?([0-9]+(\\.[0-9]*)?|\\.[0-9]+)$"
+      "description": "A real number expressed using a whole and optional fractional part separated by a period, with optional exponential notation. No leading '+' is allowed.",
+      "type": "number"
     },
     "EmailAddressDatatype": {
       "description": "An email address string formatted according to RFC 6531.",

schema/xml/metaschema-datatypes.xsd

@@ -68,17 +68,15 @@
 
 	<xs:simpleType name="DecimalDatatype">
 		<xs:annotation>
-			<xs:documentation>A real number expressed using a whole and optional fractional part
-				separated by a period.</xs:documentation>
+			<xs:documentation>
+			A real number expressed using a whole and optional fractional part
+			separated by a period, with optional exponential notation.
+			No leading '+' is allowed. Leading zeros are not allowed except
+			for the integer 0 itself or numbers less than 1 (e.g., 0.5).
+			</xs:documentation>
 		</xs:annotation>
-		<xs:restriction base="xs:decimal">
-			<xs:pattern value="\S(.*\S)?">
-				<xs:annotation>
-					<xs:documentation>This pattern ensures that leading and trailing whitespace is
-						disallowed. This helps to even the user experience between implementations
-						related to whitespace.</xs:documentation>
-				</xs:annotation>
-			</xs:pattern>
+		<xs:restriction base="xs:double">
+			<xs:pattern value="-?(0|[1-9][0-9]*)(\.[0-9]+)?([eE][+-]?[0-9]+)?"/>
 		</xs:restriction>
 	</xs:simpleType>
 

test/decimal-type/README.md

@@ -0,0 +1,57 @@
+# Decimal Datatype Test Cases
+
+This directory contains test schemas and content examples to validate the decimal datatype behavior as defined in PR #135.
+
+## Schemas
+
+- `decimal-test.xsd` - XML Schema with inline DecimalDatatype using pattern `-?(0|[1-9][0-9]*)(\.[0-9]+)?([eE][+-]?[0-9]+)?` and base type `xs:double`
+- `decimal-test.json` - JSON Schema with inline DecimalDatatype using `type: "number"`
+
+## Expected Behavior Matrix (Tested)
+
+| Test Case | Example | JSON | XML |
+|-----------|---------|:----:|:---:|
+| Integers | `12` | ✓ | ✓ |
+| Decimals | `12.34` | ✓ | ✓ |
+| Positive with leading + | `+12.34` | ✗ | ✗ |
+| Exponential notation | `1e3`, `1E+4`, `-2.5e-10` | ✓ | ✓ |
+| Leading zeros | `01.23` | ✗ | ✗ |
+| No leading digit | `.47` | ✗ | ✗ |
+| Trailing decimal point | `123.` | ✗ | ✗ |
+| Leading/trailing whitespace | ` 12.34 ` | ✓ | ✓ |
+
+**Legend:** ✓ = Valid, ✗ = Invalid
+
+### Notes
+
+Both JSON and XML ignore/normalize whitespace around numeric values, so leading/trailing whitespace is accepted in both formats.
+
+## Test Files
+
+### XML Test Cases
+
+- `xml-valid-cases.xml` - Contains values that SHOULD pass XML Schema validation
+- `xml-invalid-cases.xml` - Contains commented-out invalid cases for individual testing
+
+### JSON Test Cases
+
+- `json-valid-cases.json` - Contains values that SHOULD pass JSON Schema validation
+- `json-invalid-cases.json` - Documents invalid cases (many cannot be represented in valid JSON syntax)
+
+## Key Differences Between JSON and XML
+
+1. **Whitespace Handling**: Both XML Schema and JSON ignore whitespace around numeric values. XML Schema applies whitespace normalization (collapse) for `xs:double` before pattern matching. JSON ignores whitespace around values during parsing.
+
+2. **Syntax Restrictions**: JSON syntax itself prohibits leading `+`, leading zeros (e.g., `01.23`), `.47`, and `123.` formats, making these parse errors rather than validation errors. The XML pattern explicitly rejects these as well.
+
+## Running Validation Tests
+
+### XML Validation (using xmllint)
+```bash
+xmllint --schema decimal-test.xsd xml-valid-cases.xml --noout
+```
+
+### JSON Validation (using ajv-cli)
+```bash
+ajv validate -s decimal-test.json -d json-valid-cases.json
+```

test/decimal-type/XmlValidator.java

@@ -0,0 +1,29 @@
+import javax.xml.XMLConstants;
+import javax.xml.transform.stream.StreamSource;
+import javax.xml.validation.Schema;
+import javax.xml.validation.SchemaFactory;
+import javax.xml.validation.Validator;
+import java.io.File;
+
+public class XmlValidator {
+    public static void main(String[] args) {
+        if (args.length < 2) {
+            System.out.println("Usage: java XmlValidator <schema.xsd> <document.xml>");
+            System.exit(1);
+        }
+
+        String schemaPath = args[0];
+        String xmlPath = args[1];
+
+        try {
+            SchemaFactory factory = SchemaFactory.newInstance(XMLConstants.W3C_XML_SCHEMA_NS_URI);
+            Schema schema = factory.newSchema(new File(schemaPath));
+            Validator validator = schema.newValidator();
+            validator.validate(new StreamSource(new File(xmlPath)));
+            System.out.println(xmlPath + " is VALID");
+        } catch (Exception e) {
+            System.out.println(xmlPath + " is INVALID: " + e.getMessage());
+            System.exit(1);
+        }
+    }
+}

test/decimal-type/decimal-test.json

@@ -0,0 +1,38 @@
+{
+  "$schema": "http://json-schema.org/draft-07/schema#",
+  "$id": "http://csrc.nist.gov/ns/metaschema/test/decimal/decimal-test-schema.json",
+  "$comment": "Schema for testing decimal datatype validation",
+  "type": "object",
+  "properties": {
+    "decimal-tests": {
+      "type": "object",
+      "properties": {
+        "test-cases": {
+          "type": "array",
+          "items": {
+            "type": "object",
+            "properties": {
+              "id": {
+                "type": "string"
+              },
+              "description": {
+                "type": "string"
+              },
+              "expected": {
+                "type": "string",
+                "enum": ["valid", "invalid"]
+              },
+              "value": {
+                "description": "A real number expressed using a whole and optional fractional part separated by a period, with optional exponential notation. No leading '+' is allowed.",
+                "type": "number"
+              }
+            },
+            "required": ["id", "description", "expected", "value"]
+          }
+        }
+      },
+      "required": ["test-cases"]
+    }
+  },
+  "required": ["decimal-tests"]
+}

test/decimal-type/decimal-test.xsd

@@ -0,0 +1,46 @@
+<?xml version="1.0" encoding="utf-8"?>
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
+    xmlns:m="http://csrc.nist.gov/ns/metaschema/test/decimal"
+    targetNamespace="http://csrc.nist.gov/ns/metaschema/test/decimal"
+    elementFormDefault="qualified">
+
+    <!-- Root element for testing -->
+    <xs:element name="decimal-tests">
+        <xs:complexType>
+            <xs:sequence>
+                <xs:element name="test-case" maxOccurs="unbounded">
+                    <xs:complexType>
+                        <xs:sequence>
+                            <xs:element name="value">
+                                <xs:simpleType>
+                                    <xs:annotation>
+                                        <xs:documentation>
+                                        A real number expressed using a whole and optional fractional part
+                                        separated by a period, with optional exponential notation.
+                                        No leading '+' is allowed. Leading zeros are not allowed except
+                                        for the integer 0 itself or numbers less than 1 (e.g., 0.5).
+                                        </xs:documentation>
+                                    </xs:annotation>
+                                    <xs:restriction base="xs:double">
+                                        <xs:pattern value="-?(0|[1-9][0-9]*)(\.[0-9]+)?([eE][+-]?[0-9]+)?"/>
+                                    </xs:restriction>
+                                </xs:simpleType>
+                            </xs:element>
+                        </xs:sequence>
+                        <xs:attribute name="id" type="xs:string" use="required"/>
+                        <xs:attribute name="description" type="xs:string" use="required"/>
+                        <xs:attribute name="expected" use="required">
+                            <xs:simpleType>
+                                <xs:restriction base="xs:string">
+                                    <xs:enumeration value="valid"/>
+                                    <xs:enumeration value="invalid"/>
+                                </xs:restriction>
+                            </xs:simpleType>
+                        </xs:attribute>
+                    </xs:complexType>
+                </xs:element>
+            </xs:sequence>
+        </xs:complexType>
+    </xs:element>
+
+</xs:schema>

test/decimal-type/json-invalid-cases.json

@@ -0,0 +1,47 @@
+{
+  "$schema": "decimal-test.json",
+  "_comment": "Invalid decimal test cases for JSON validation. These values SHOULD FAIL JSON Schema validation or are invalid JSON syntax.",
+  "_note": "JSON does not allow: leading +, leading/trailing whitespace, .47 syntax, 123. syntax. These would be syntax errors or string values.",
+  "decimal-tests": {
+    "test-cases": [
+      {
+        "id": "json-placeholder",
+        "description": "Placeholder - see comments below for invalid cases that cannot be represented in JSON",
+        "expected": "valid",
+        "value": 0
+      }
+    ]
+  },
+  "_invalid_cases_documentation": {
+    "leading_plus": {
+      "example": "+12.34",
+      "reason": "JSON syntax does not allow leading + on numbers. This would be a parse error.",
+      "expected": "invalid"
+    },
+    "leading_zeros": {
+      "example": "01.23",
+      "reason": "JSON syntax does not allow leading zeros on numbers (except 0 itself). This would be a parse error.",
+      "expected": "invalid"
+    },
+    "no_leading_digit": {
+      "example": ".47",
+      "reason": "JSON syntax requires a digit before the decimal point. This would be a parse error.",
+      "expected": "invalid"
+    },
+    "trailing_decimal": {
+      "example": "123.",
+      "reason": "JSON syntax requires digits after the decimal point. This would be a parse error.",
+      "expected": "invalid"
+    },
+    "leading_whitespace": {
+      "example": " 12.34",
+      "reason": "If represented as a string \" 12.34\", it would fail type: number validation.",
+      "expected": "invalid"
+    },
+    "trailing_whitespace": {
+      "example": "12.34 ",
+      "reason": "If represented as a string \"12.34 \", it would fail type: number validation.",
+      "expected": "invalid"
+    }
+  }
+}

test/decimal-type/json-test-string-value.json

@@ -0,0 +1,13 @@
+{
+  "$schema": "decimal-test.json",
+  "decimal-tests": {
+    "test-cases": [
+      {
+        "id": "json-string-with-whitespace",
+        "description": "String value with whitespace should fail type: number",
+        "expected": "invalid",
+        "value": " 12.34 "
+      }
+    ]
+  }
+}

test/decimal-type/json-valid-cases.json

@@ -0,0 +1,68 @@
+{
+  "$schema": "decimal-test.json",
+  "_comment": "Valid decimal test cases for JSON validation. All values SHOULD pass JSON Schema validation with type: number",
+  "decimal-tests": {
+    "test-cases": [
+      {
+        "id": "json-int-positive",
+        "description": "Positive integer (e.g., 12)",
+        "expected": "valid",
+        "value": 12
+      },
+      {
+        "id": "json-int-negative",
+        "description": "Negative integer",
+        "expected": "valid",
+        "value": -42
+      },
+      {
+        "id": "json-int-zero",
+        "description": "Zero",
+        "expected": "valid",
+        "value": 0
+      },
+      {
+        "id": "json-dec-positive",
+        "description": "Positive decimal (e.g., 12.34)",
+        "expected": "valid",
+        "value": 12.34
+      },
+      {
+        "id": "json-dec-negative",
+        "description": "Negative decimal",
+        "expected": "valid",
+        "value": -12.34
+      },
+      {
+        "id": "json-dec-small",
+        "description": "Small decimal",
+        "expected": "valid",
+        "value": 0.001
+      },
+      {
+        "id": "json-exp-lower",
+        "description": "Exponential notation lowercase (e.g., 1e3) - Valid in JSON",
+        "expected": "valid",
+        "value": 1e3
+      },
+      {
+        "id": "json-exp-upper-plus",
+        "description": "Exponential notation uppercase with plus (e.g., 1E+4) - Valid in JSON",
+        "expected": "valid",
+        "value": 1E+4
+      },
+      {
+        "id": "json-exp-negative",
+        "description": "Exponential notation negative (e.g., -2.5e-10) - Valid in JSON",
+        "expected": "valid",
+        "value": -2.5e-10
+      },
+      {
+        "id": "json-decimal-no-leading-zero",
+        "description": "Decimal without unnecessary leading zeros (1.23 is valid; 01.23 is invalid JSON syntax)",
+        "expected": "valid",
+        "value": 1.23
+      }
+    ]
+  }
+}

test/decimal-type/xml-invalid-cases.xml

@@ -0,0 +1,26 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  Invalid decimal test cases for XML validation.
+  Each test-case is in a separate file because invalid values cause validation to fail.
+  This file documents all invalid cases and their expected behavior.
+
+  Test files:
+  - xml-test-leading-plus.xml: +12.34 (INVALID - leading + not allowed)
+  - xml-test-leading-zero.xml: 01.23 (INVALID - leading zeros not allowed)
+  - xml-test-no-leading-digit.xml: .47 (INVALID - must have digit before decimal)
+  - xml-test-trailing-decimal.xml: 123. (INVALID - must have digit after decimal)
+  - xml-test-leading-whitespace.xml: " 12.34" (VALID due to xs:double whitespace collapse)
+
+  Note: Leading/trailing whitespace passes validation because xs:double
+  applies whitespace normalization before pattern matching.
+-->
+<decimal-tests xmlns="http://csrc.nist.gov/ns/metaschema/test/decimal"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://csrc.nist.gov/ns/metaschema/test/decimal decimal-test.xsd">
+
+    <!-- This is a placeholder. See individual xml-test-*.xml files for actual invalid cases. -->
+    <test-case id="placeholder" description="Placeholder - see individual test files" expected="valid">
+        <value>0</value>
+    </test-case>
+
+</decimal-tests>

test/decimal-type/xml-test-leading-plus.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<decimal-tests xmlns="http://csrc.nist.gov/ns/metaschema/test/decimal"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://csrc.nist.gov/ns/metaschema/test/decimal decimal-test.xsd">
+    <test-case id="xml-leading-plus" description="Leading plus sign (e.g., +12.34)" expected="invalid">
+        <value>+12.34</value>
+    </test-case>
+</decimal-tests>

test/decimal-type/xml-test-leading-whitespace.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<decimal-tests xmlns="http://csrc.nist.gov/ns/metaschema/test/decimal"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://csrc.nist.gov/ns/metaschema/test/decimal decimal-test.xsd">
+    <test-case id="xml-leading-whitespace" description="Leading whitespace (passes due to xs:double whitespace collapse)" expected="valid">
+        <value> 12.34</value>
+    </test-case>
+</decimal-tests>

test/decimal-type/xml-test-leading-zero.xml

@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<decimal-tests xmlns="http://csrc.nist.gov/ns/metaschema/test/decimal"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://csrc.nist.gov/ns/metaschema/test/decimal decimal-test.xsd">
+    <test-case id="xml-leading-zero" description="Leading zeros (e.g., 01.23)" expected="invalid">
+        <value>01.23</value>
+    </test-case>
+</decimal-tests>