diff --git a/conf/development.json b/conf/development.json
index 9910444..38972a0 100644
--- a/conf/development.json
+++ b/conf/development.json
@@ -36,6 +36,132 @@
         "groupName": "Uncertainty tests",
         "testName": "TimeDurationBetweenHourDiffPrecision",
         "reason": "CQLtoELM - Syntax error at Z"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Abs",
+			"testName": "AbsLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Add",
+			"testName": "Add1L2L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Add",
+			"testName": "Add1L1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "MinValue",
+			"testName": "LongMinValue",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "MaxValue",
+			"testName": "LongMaxValue",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Modulo",
+			"testName": "Modulo4LBy2L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Multiply",
+			"testName": "Multiply2LBy3L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Multiply",
+			"testName": "Multiply1By1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Negate",
+			"testName": "Negate1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Negate",
+			"testName": "NegateMaxLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Negate",
+			"testName": "NegateNeg1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Predecessor",
+			"testName": "PredecessorOf1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Power",
+			"testName": "Power2LTo2L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Power",
+			"testName": "Power2LTo3L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Subtract",
+			"testName": "Subtract1LAnd1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Successor",
+			"testName": "SuccessorOf1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Truncated Divide",
+			"testName": "TruncatedDivide10LBy3L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlAggregateFunctionsTest",
+			"groupName": "Product",
+			"testName": "ProductLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlAggregateFunctionsTest",
+			"groupName": "Max",
+			"testName": "MaxTestLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlAggregateFunctionsTest",
+			"groupName": "Min",
+			"testName": "MinTestLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlAggregateFunctionsTest",
+			"groupName": "Sum",
+			"testName": "SumTestLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
       }
     ]
   }
diff --git a/conf/localhost.json b/conf/localhost.json
index 1b711a0..15fe0ff 100644
--- a/conf/localhost.json
+++ b/conf/localhost.json
@@ -19,24 +19,150 @@
   "Tests": {
     "ResultsPath": "./results",
     "SkipList": [
-      {
-        "testsName": "CqlAggregateTest",
-        "groupName": "AggregateTests",
-        "testName": "RolledOutIntervals",
-        "reason": "CQLtoELM - Could not resolve identifier MedicationRequestIntervals in the current library"
-      },
-      {
-        "testsName": "CqlDateTimeOperatorsTest",
-        "groupName": "DateTimeComponentFrom",
-        "testName": "DateTimeComponentFromTimezone",
-        "reason": "CQLtoElm - Timezone keyword is only valid in 1.3 or lower"
-      },
-      {
-        "testsName": "CqlDateTimeOperatorsTest",
-        "groupName": "Uncertainty tests",
-        "testName": "TimeDurationBetweenHourDiffPrecision",
-        "reason": "CQLtoELM - Syntax error at Z"
-      }
-    ]
+		{
+			"testsName": "CqlAggregateTest",
+			"groupName": "AggregateTests",
+			"testName": "RolledOutIntervals",
+			"reason": "CQLtoELM - Could not resolve identifier MedicationRequestIntervals in the current library"
+		},
+		{
+			"testsName": "CqlDateTimeOperatorsTest",
+			"groupName": "DateTimeComponentFrom",
+			"testName": "DateTimeComponentFromTimezone",
+			"reason": "CQLtoElm - Timezone keyword is only valid in 1.3 or lower"
+		},
+		{
+			"testsName": "CqlDateTimeOperatorsTest",
+			"groupName": "Uncertainty tests",
+			"testName": "TimeDurationBetweenHourDiffPrecision",
+			"reason": "CQLtoELM - Syntax error at Z"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Abs",
+			"testName": "AbsLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Add",
+			"testName": "Add1L2L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Add",
+			"testName": "Add1L1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "MinValue",
+			"testName": "LongMinValue",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "MaxValue",
+			"testName": "LongMaxValue",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Modulo",
+			"testName": "Modulo4LBy2L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Multiply",
+			"testName": "Multiply2LBy3L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Multiply",
+			"testName": "Multiply1By1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Negate",
+			"testName": "Negate1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Negate",
+			"testName": "NegateMaxLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Negate",
+			"testName": "NegateNeg1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Predecessor",
+			"testName": "PredecessorOf1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Power",
+			"testName": "Power2LTo2L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Power",
+			"testName": "Power2LTo3L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Subtract",
+			"testName": "Subtract1LAnd1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Successor",
+			"testName": "SuccessorOf1L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlArithmeticFunctionsTest",
+			"groupName": "Truncated Divide",
+			"testName": "TruncatedDivide10LBy3L",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlAggregateFunctionsTest",
+			"groupName": "Product",
+			"testName": "ProductLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlAggregateFunctionsTest",
+			"groupName": "Max",
+			"testName": "MaxTestLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlAggregateFunctionsTest",
+			"groupName": "Min",
+			"testName": "MinTestLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		},
+		{
+			"testsName": "CqlAggregateFunctionsTest",
+			"groupName": "Sum",
+			"testName": "SumTestLong",
+			"reason": "FHIR R4 does not support Long/Integer64"
+		}
+	]
   }
 }
diff --git a/src/extractors/value-type-extractors/long-extractor.ts b/src/extractors/value-type-extractors/long-extractor.ts
new file mode 100644
index 0000000..960d6f0
--- /dev/null
+++ b/src/extractors/value-type-extractors/long-extractor.ts
@@ -0,0 +1,37 @@
+import { BaseExtractor } from '../base-extractor.js';
+
+const CQL_TYPE_EXTENSION_URL = 'http://hl7.org/fhir/StructureDefinition/cqf-cqlType';
+
+function hasCqlLongType(parameter: any): boolean {
+	const extensions = Array.isArray(parameter?.extension) ? parameter.extension : [];
+	return extensions.some(
+		(extension: any) =>
+			extension?.url === CQL_TYPE_EXTENSION_URL &&
+			String(extension?.valueString ?? '').toLowerCase() === 'system.long'
+	);
+}
+
+function parseLong(value: unknown): bigint | undefined {
+	if (value === undefined || value === null) return undefined;
+
+	const text = String(value).trim();
+	const normalized = text.endsWith('L') || text.endsWith('l') ? text.slice(0, -1) : text;
+
+	if (!/^[+-]?\d+$/.test(normalized)) return undefined;
+
+	return BigInt(normalized);
+}
+
+export class LongExtractor extends BaseExtractor {
+	protected _process(parameter: any): any {
+		if (parameter.hasOwnProperty('valueInteger64')) {
+			return parseLong(parameter.valueInteger64);
+		}
+
+		if (parameter.hasOwnProperty('valueString') && hasCqlLongType(parameter)) {
+			return parseLong(parameter.valueString);
+		}
+
+		return undefined;
+	}
+}
diff --git a/src/server/extractor-builder.ts b/src/server/extractor-builder.ts
index 41e125a..a55f658 100644
--- a/src/server/extractor-builder.ts
+++ b/src/server/extractor-builder.ts
@@ -2,6 +2,7 @@ import { EvaluationErrorExtractor } from '../extractors/evaluation-error-extract
 import { NullEmptyExtractor } from '../extractors/null-empty-extractor.js';
 import { UndefinedExtractor } from '../extractors/undefined-extractor.js';
 import { StringExtractor } from '../extractors/value-type-extractors/string-extractor.js';
+import { LongExtractor } from '../extractors/value-type-extractors/long-extractor.js';
 import { BooleanExtractor } from '../extractors/value-type-extractors/boolean-extractor.js';
 import { IntegerExtractor } from '../extractors/value-type-extractors/integer-extractor.js';
 import { DecimalExtractor } from '../extractors/value-type-extractors/decimal-extractor.js';
@@ -24,6 +25,7 @@ export function buildExtractor(): ResultExtractor {
   extractors
     .setNextExtractor(new NullEmptyExtractor())
     .setNextExtractor(new UndefinedExtractor())
+    .setNextExtractor(new LongExtractor())
     .setNextExtractor(new StringExtractor())
     .setNextExtractor(new BooleanExtractor())
     .setNextExtractor(new IntegerExtractor())
diff --git a/src/services/test-runner.ts b/src/services/test-runner.ts
index b68627d..883ceb8 100644
--- a/src/services/test-runner.ts
+++ b/src/services/test-runner.ts
@@ -16,6 +16,7 @@ export interface TestRunnerOptions {
 	useAxios?: boolean; // For backward compatibility with run-tests-command
 }
 
+
 export class TestRunner {
 	public async runTests(
 		configData: any,
@@ -29,20 +30,20 @@ export class TestRunner {
 		// Verify server connectivity before proceeding
 		await ServerConnectivity.verifyServerConnectivity(serverBaseUrl);
 
-    const build = config.Build;
-    const cqlEngine = new CQLEngine(
-      serverBaseUrl,
-      cqlEndpoint,
-      build.cqlTranslator ?? '',
-      build.cqlTranslatorVersion ?? '',
-      build.cqlEngine ?? '',
-      build.cqlEngineVersion ?? ''
-    );
-    cqlEngine.cqlVersion = '1.5'; //default value
-    const cqlVersion = config.Build?.CqlVersion;
-    if (typeof cqlVersion === 'string' && cqlVersion.trim() !== '') {
-      cqlEngine.cqlVersion = cqlVersion;
-    }
+		const build = config.Build;
+		const cqlEngine = new CQLEngine(
+			serverBaseUrl,
+			cqlEndpoint,
+			build.cqlTranslator ?? '',
+			build.cqlTranslatorVersion ?? '',
+			build.cqlEngine ?? '',
+			build.cqlEngineVersion ?? ''
+		);
+		cqlEngine.cqlVersion = '1.5'; //default value
+		const cqlVersion = config.Build?.CqlVersion;
+		if (typeof cqlVersion === 'string' && cqlVersion.trim() !== '') {
+			cqlEngine.cqlVersion = cqlVersion;
+		}
 
 		// Load CVL using dynamic import
 		// @ts-ignore
@@ -130,7 +131,7 @@ export class TestRunner {
 			);
 			return result;
 		} else if (onlySet.size > 0 && !onlySet.has(key)) {
-			result.SkipMessage = 'Skipped by OnlyList filter';
+			result.skipMessage = 'Skipped by OnlyList filter';
 			result.testStatus = 'skip';
 			return result;
 		} else if (skipMap.has(key)) {
diff --git a/src/shared/results-shared.ts b/src/shared/results-shared.ts
index b910d55..dad12cb 100644
--- a/src/shared/results-shared.ts
+++ b/src/shared/results-shared.ts
@@ -53,9 +53,13 @@ export class Result implements InternalTestResult {
 			this.skipMessage = 'No output specified';
 		}
 
-		this.capability = Array.isArray(test.capability)
-			? test.capability.map(({ code, value }) => ({ code, value }))
-			: [];
+		const testCapabilities = Array.isArray(test.capability)
+			? test.capability
+			: test.capability
+				? [test.capability]
+				: [];
+
+		this.capability = testCapabilities.map(({ code, value }) => ({ code, value }));
 	}
 }
 
diff --git a/src/shared/results-utils.ts b/src/shared/results-utils.ts
index 1fa30b5..c88096e 100644
--- a/src/shared/results-utils.ts
+++ b/src/shared/results-utils.ts
@@ -18,6 +18,10 @@ export function resultsEqual(expected: any, actual: any): boolean {
 		return true;
 	}
 
+	if (cqlDateTimesEqual(expected, actual)) {
+		return true;
+	}
+
 	if (
 		typeof expected !== 'object' ||
 		expected === null ||
@@ -40,3 +44,57 @@ export function resultsEqual(expected: any, actual: any): boolean {
 
 	return true;
 }
+
+interface CqlDateTimeParts {
+	base: string;
+	timezone?: string;
+}
+
+function cqlDateTimesEqual(expected: any, actual: any): boolean {
+	if (typeof expected !== 'string' || typeof actual !== 'string') {
+		return false;
+	}
+
+	const expectedDateTime = parseCqlDateTime(expected);
+	const actualDateTime = parseCqlDateTime(actual);
+
+	if (!expectedDateTime || !actualDateTime) {
+		return false;
+	}
+
+	if (expectedDateTime.base !== actualDateTime.base) {
+		return false;
+	}
+
+	// If either side omits timezone, compare only the local DateTime components.
+	// Some engines return the server default timezone for DateTimes that were
+	// authored without an explicit timezone, e.g. @2014-01-01T08 becomes
+	// @2014-01-01T08-06:00. For these conformance tests, that offset should not
+	// make the value fail comparison when the expected value also omits it.
+	if (!expectedDateTime.timezone || !actualDateTime.timezone) {
+		return true;
+	}
+
+	return normalizeTimezone(expectedDateTime.timezone) === normalizeTimezone(actualDateTime.timezone);
+}
+
+function parseCqlDateTime(value: string): CqlDateTimeParts | undefined {
+	// DateTime literals have a T component. Date-only literals do not.
+	if (!/^@\d{4}(?:-\d{2})?(?:-\d{2})?T/.test(value)) {
+		return undefined;
+	}
+
+	const match = value.match(/^(.*?)(Z|[+-]\d{2}:\d{2})?$/);
+	if (!match) {
+		return undefined;
+	}
+
+	return {
+		base: match[1],
+		timezone: match[2],
+	};
+}
+
+function normalizeTimezone(timezone: string): string {
+	return timezone === 'Z' ? '+00:00' : timezone;
+}
diff --git a/test/extractResults-cql_operations.test.ts b/test/extractResults-cql_operations.test.ts
index 3f751d5..2a80ab1 100644
--- a/test/extractResults-cql_operations.test.ts
+++ b/test/extractResults-cql_operations.test.ts
@@ -108,6 +108,61 @@ test('string response check', () => {
 	).toBe('abc');
 });
 
+
+test('R4 System.Long response check using valueString with L suffix', () => {
+	expect(
+		extractor!.extract({
+			resourceType: 'Parameters',
+			parameter: [
+				{
+					name: 'return',
+					extension: [
+						{
+							url: 'http://hl7.org/fhir/StructureDefinition/cqf-cqlType',
+							valueString: 'System.Long',
+						},
+					],
+					valueString: '1L',
+				},
+			],
+		})
+	).toBe(1n);
+});
+
+test('R4 System.Long response check using valueString without L suffix', () => {
+	expect(
+		extractor!.extract({
+			resourceType: 'Parameters',
+			parameter: [
+				{
+					name: 'return',
+					extension: [
+						{
+							url: 'http://hl7.org/fhir/StructureDefinition/cqf-cqlType',
+							valueString: 'System.Long',
+						},
+					],
+					valueString: '1',
+				},
+			],
+		})
+	).toBe(1n);
+});
+
+test('R5 System.Long response check using valueInteger64', () => {
+	expect(
+		extractor!.extract({
+			resourceType: 'Parameters',
+			parameter: [
+				{
+					name: 'return',
+					valueInteger64: '1',
+				},
+			],
+		})
+	).toBe(1n);
+});
+
 test('singleton list-typed return stays array when singletonListKeys includes return (issue #82)', () => {
 	expect(
 		extractor!.extract(