diff --git a/Sources/ForgeOffload/MHL.swift b/Sources/ForgeOffload/MHL.swift
index 1c81220..021381d 100644
--- a/Sources/ForgeOffload/MHL.swift
+++ b/Sources/ForgeOffload/MHL.swift
@@ -1,8 +1,10 @@
 import Foundation
 
-/// Media Hash List (ASC MHL-style) manifest: per-file path/size/xxh64.
-/// Structure follows MHL v2 hashlist shape; full ASC MHL chain/directory
-/// hashes can layer on later without breaking this format.
+/// ASC Media Hash List v2.0 (urn:ASC:MHL:v2.0) manifest.
+/// Structure per official XSD (github.com/ascmitc/mhl, xsd/ASCMHL.xsd):
+/// hashlist > creatorinfo (creationdate, hostname, tool) + processinfo (process)
+/// + hashes > hash > path[@size] + <xxh64 action hashdate>.
+/// Findings documented in docs/research/red-rcp2-protocol.md (MHL section).
 public enum MHL {
 
     public struct Failure: Equatable, Sendable {
@@ -33,17 +35,35 @@ public enum MHL {
             .replacingOccurrences(of: "&amp;", with: "&")
     }
 
-    /// Build manifest XML for files (relative paths) under root.
-    public static func generate(root: String, creator: String, files: [String]) throws -> String {
+    private static func isoNow() -> String {
+        ISO8601DateFormatter().string(from: Date())
+    }
+
+    private static func hostname() -> String {
+        ProcessInfo.processInfo.hostName
+    }
+
+    /// Build ASC MHL v2.0 manifest XML for files (relative paths) under root.
+    /// process: "transfer" for offloads, "in-place" for verification-only seals.
+    public static func generate(
+        root: String,
+        creator: String,
+        files: [String],
+        process: String = "transfer"
+    ) throws -> String {
         let fm = FileManager.default
-        let dateFormatter = ISO8601DateFormatter()
+        let now = isoNow()
         var out = """
         <?xml version="1.0" encoding="UTF-8"?>
-        <hashlist version="2.0">
+        <hashlist version="2.0" xmlns="urn:ASC:MHL:v2.0">
           <creatorinfo>
-            <creationdate>\(dateFormatter.string(from: Date()))</creationdate>
-            <tool>\(escape(creator))</tool>
+            <creationdate>\(now)</creationdate>
+            <hostname>\(escape(hostname()))</hostname>
+            <tool version="0.1">\(escape(creator))</tool>
           </creatorinfo>
+          <processinfo>
+            <process>\(process)</process>
+          </processinfo>
           <hashes>
 
         """
@@ -56,9 +76,8 @@ public enum MHL {
             let hash = try FileHasher.xxh64(path: full)
             out += """
                 <hash>
-                  <path>\(escape(rel))</path>
-                  <size>\(size)</size>
-                  <xxh64>\(hash)</xxh64>
+                  <path size="\(size)">\(escape(rel))</path>
+                  <xxh64 action="original" hashdate="\(now)">\(hash)</xxh64>
                 </hash>
 
             """
@@ -68,8 +87,14 @@ public enum MHL {
     }
 
     /// Write manifest to file.
-    public static func write(root: String, creator: String, files: [String], to path: String) throws {
-        let xml = try generate(root: root, creator: creator, files: files)
+    public static func write(
+        root: String,
+        creator: String,
+        files: [String],
+        to path: String,
+        process: String = "transfer"
+    ) throws {
+        let xml = try generate(root: root, creator: creator, files: files, process: process)
         try xml.write(toFile: path, atomically: true, encoding: .utf8)
     }
 
@@ -84,10 +109,12 @@ public enum MHL {
                 failures.append(Failure(path: e.path, reason: .missing))
                 continue
             }
-            let size = (try fm.attributesOfItem(atPath: full)[.size] as? UInt64) ?? 0
-            if size != e.size {
-                failures.append(Failure(path: e.path, reason: .sizeMismatch))
-                continue
+            if let expectedSize = e.size {
+                let size = (try fm.attributesOfItem(atPath: full)[.size] as? UInt64) ?? 0
+                if size != expectedSize {
+                    failures.append(Failure(path: e.path, reason: .sizeMismatch))
+                    continue
+                }
             }
             let hash = try FileHasher.xxh64(path: full)
             if hash != e.xxh64 {
@@ -99,11 +126,12 @@ public enum MHL {
 
     struct Entry {
         let path: String
-        let size: UInt64
+        let size: UInt64?
         let xxh64: String
     }
 
-    /// Scanner-based parse of <hash> blocks.
+    /// Scanner-based parse of <hash> blocks. Accepts v2.0 attribute-style size
+    /// and (legacy, our v1) element-style <size>.
     static func parse(_ xml: String) throws -> [Entry] {
         guard xml.contains("<hashlist") else {
             throw OffloadError.readFailed("not an MHL manifest")
@@ -113,18 +141,37 @@ public enum MHL {
         while let blockStart = xml.range(of: "<hash>", range: searchRange),
               let blockEnd = xml.range(of: "</hash>", range: blockStart.upperBound..<xml.endIndex) {
             let block = String(xml[blockStart.upperBound..<blockEnd.lowerBound])
-            func field(_ tag: String) -> String? {
-                guard let open = block.range(of: "<\(tag)>"),
-                      let close = block.range(of: "</\(tag)>"),
-                      open.upperBound <= close.lowerBound else { return nil }
-                return String(block[open.upperBound..<close.lowerBound])
+
+            // Path element with optional attributes: <path size="N" ...>rel</path>
+            guard let pathOpen = block.range(of: "<path"),
+                  let pathTagEnd = block.range(of: ">", range: pathOpen.upperBound..<block.endIndex),
+                  let pathClose = block.range(of: "</path>", range: pathTagEnd.upperBound..<block.endIndex) else {
+                throw OffloadError.readFailed("malformed <hash> entry: no path")
             }
-            guard let path = field("path"),
-                  let sizeStr = field("size"), let size = UInt64(sizeStr),
-                  let hash = field("xxh64") else {
-                throw OffloadError.readFailed("malformed <hash> entry")
+            let pathAttrs = String(block[pathOpen.upperBound..<pathTagEnd.lowerBound])
+            let path = unescape(String(block[pathTagEnd.upperBound..<pathClose.lowerBound]))
+
+            // size attribute (v2.0) or legacy <size> element.
+            var size: UInt64?
+            if let m = pathAttrs.range(of: "size=\"") {
+                let rest = pathAttrs[m.upperBound...]
+                if let q = rest.firstIndex(of: "\"") {
+                    size = UInt64(rest[..<q])
+                }
+            } else if let sizeOpen = block.range(of: "<size>"),
+                      let sizeClose = block.range(of: "</size>") {
+                size = UInt64(block[sizeOpen.upperBound..<sizeClose.lowerBound].trimmingCharacters(in: .whitespacesAndNewlines))
             }
-            entries.append(Entry(path: unescape(path), size: size, xxh64: hash))
+
+            // xxh64 element with optional attributes.
+            guard let hOpen = block.range(of: "<xxh64"),
+                  let hTagEnd = block.range(of: ">", range: hOpen.upperBound..<block.endIndex),
+                  let hClose = block.range(of: "</xxh64>", range: hTagEnd.upperBound..<block.endIndex) else {
+                throw OffloadError.readFailed("malformed <hash> entry: no xxh64")
+            }
+            let hash = String(block[hTagEnd.upperBound..<hClose.lowerBound]).trimmingCharacters(in: .whitespacesAndNewlines)
+
+            entries.append(Entry(path: path, size: size, xxh64: hash))
             searchRange = blockEnd.upperBound..<xml.endIndex
         }
         guard !entries.isEmpty else {
diff --git a/Tests/ForgeOffloadTests/MHLTests.swift b/Tests/ForgeOffloadTests/MHLTests.swift
index 49499dc..4d35ec0 100644
--- a/Tests/ForgeOffloadTests/MHLTests.swift
+++ b/Tests/ForgeOffloadTests/MHLTests.swift
@@ -18,14 +18,23 @@ final class MHLTests: XCTestCase {
     }
 
     // MHL XML structure: hashlist root, creatorinfo, hash entries with file/size/xxh64.
+    // ASC MHL v2.0 XSD shape (urn:ASC:MHL:v2.0):
+    // hashlist > creatorinfo (creationdate, hostname, tool) + processinfo (process)
+    // + hashes > hash > path[@size] + xxh64[@action][@hashdate].
     func testWriteStructure() throws {
         let xml = try MHL.generate(root: root, creator: "Forge 0.1", files: ["CLIPS/C001.mov", "CLIPS/C002.mov"])
-        XCTAssertTrue(xml.hasPrefix("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<hashlist version=\"2.0\">"))
+        XCTAssertTrue(xml.hasPrefix("<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n<hashlist version=\"2.0\" xmlns=\"urn:ASC:MHL:v2.0\">"))
         XCTAssertTrue(xml.contains("<creatorinfo>"))
-        XCTAssertTrue(xml.contains("<tool>Forge 0.1</tool>"))
-        XCTAssertTrue(xml.contains("<path>CLIPS/C001.mov</path>"))
-        XCTAssertTrue(xml.contains("<size>17</size>"))
-        XCTAssertTrue(xml.contains("<xxh64>"))
+        XCTAssertTrue(xml.contains("<creationdate>"))
+        XCTAssertTrue(xml.contains("<hostname>"))
+        XCTAssertTrue(xml.contains("<tool version=\"0.1\">Forge 0.1</tool>"))
+        // processinfo required by XSD; offload = transfer.
+        XCTAssertTrue(xml.contains("<processinfo>"))
+        XCTAssertTrue(xml.contains("<process>transfer</process>"))
+        // size is a path ATTRIBUTE per XSD, not an element.
+        XCTAssertTrue(xml.contains("<path size=\"17\">CLIPS/C001.mov</path>"))
+        XCTAssertTrue(xml.contains("<xxh64 action=\"original\" hashdate="))
+        XCTAssertFalse(xml.contains("<size>"))
         XCTAssertTrue(xml.hasSuffix("</hashlist>\n"))
     }
 
@@ -76,7 +85,7 @@ final class MHLTests: XCTestCase {
     func testPathEscaping() throws {
         try Data("x".utf8).write(to: URL(fileURLWithPath: root + "/a&b.mov"))
         let xml = try MHL.generate(root: root, creator: "Forge", files: ["a&b.mov"])
-        XCTAssertTrue(xml.contains("<path>a&amp;b.mov</path>"))
+        XCTAssertTrue(xml.contains(">a&amp;b.mov</path>"))
         let result = try MHL.verify(manifest: xml, root: root)
         XCTAssertTrue(result.passed)
     }