Update kernel/binary.md.

pkg/kernel/binary.md

 This file describes the binary format of Dart Kernel.
 
 Notation
 --------
 Bitmasks are described with the syntax:
 ```scala
     Byte flags (flag1, flag2, ..., flagN)
 ```
 where 'flag<N>' is the N-th least significant bit,
 (so flag1 is the least significant bit).
@@ skipping 24 matching lines @@
 
 type UInt30 extends UInt {
   Byte byte1(11xxxxxx); // most significant byte, discard the two high bits.
   Byte byte2(xxxxxxxx);
   Byte byte3(xxxxxxxx);
   Byte byte4(xxxxxxxx); // least significant byte
 }
 
 type MagicWord = big endian 32-bit unsigned integer
 
-type String {
-  UInt num_bytes;
-  Byte[num_bytes] utf8_bytes;
-}
-
-type StringTable {
-  UInt num_strings;
-  String[num_strings] strings;
-}
-
-type StringReference {
-  UInt index; // Index into the StringTable.
-}
-
-type LineStarts {
-  UInt lineCount;
-  // Delta encoded, e.g. 0, 10, 15, 7, 10 means 0, 10, 25, 32, 42.
-  UInt[lineCount] lineStarts;
-}
-
-type UriLineStarts {
-  StringTable uris;
-  LineStarts[uris.num_strings] lineStarts;
-}
-
-type UriReference {
-  UInt index; // Index into the URIs StringTable.
-}
-
-type FileOffset {
-  // Saved as number+1 to accommodate literal "-1".
-  UInt fileOffset;
-}
-
 type List<T> {
   UInt length;
   T[length] items;
 }
 
+type String {
+  List<Byte> utf8Bytes;
+}
+
+type StringTable {
+  List<String> strings;
+}
+
+type StringReference {
+  UInt index; // Index into the StringTable strings.
+}
+
+type LineStarts {
+  // Line starts are delta-encoded (they are encoded as line lengths).  The list
+  // [0, 10, 25, 32, 42] is encoded as [0, 10, 15, 7, 10].
+  List<Uint> lineStarts;
+}
+
+type UriLineStarts {
+  List<String> uris;
+  LineStarts[uris.length] lineStarts;
+}
+
+type UriReference {
+  UInt index; // Index into the UriLineStarts uris.
+}
+
+type FileOffset {
+  // Encoded as offset + 1 to accommodate -1 indicating no offset.
+  UInt fileOffset;
+}
+
 type Option<T> {
   Byte tag;
 }
 type Nothing extends Option<T> {
   Byte tag = 0;
 }
 type Something<T> extends Option<T> {
   Byte tag = 1;
   T value;
 }
 
 type ProgramFile {
   MagicWord magic = 0x90ABCDEF;
   StringTable strings;
   UriLineStarts lineStartsMap;
-  List<Library> library;
+  List<Library> libraries;
   LibraryProcedureReference mainMethod;
 }
 
 type LibraryReference {
-  // For library files, this is an index into the import table.
-  // For program files, this is an index into the list of libaries.
+  // Index into the ProgramFile libraries.
   UInt index;
 }
 
 abstract type ClassReference {}
 
 type NormalClassReference extends ClassReference {
   Byte tag = 100;
   LibraryReference library;
   UInt classIndex;
 }
@@ skipping 46 matching lines @@
 type Name {
   StringReference name;
   if name begins with '_' {
     LibraryReference library;
   }
 }
 
 type Library {
   Byte flags (isExternal);
   StringReference name;
-  // A URI with the dart, package, or file scheme.  For file URIs, the path
-  // is an absolute path to the .dart file from which the library was created.
+  // A URI from which the library was created.  The URI has the dart, package,
+  // file, or app scheme.  For file URIs, the path is an absolute path to the
+  // .dart file from which the library was created.  For app URIs, the path is
+  // relative to an application root that was specified when the binary was
+  // generated.
   StringReference importUri;
   // An absolute path URI to the .dart file from which the library was created.
   UriReference fileUri;
   List<Class> classes;
   List<Field> fields;
   List<Procedure> procedures;
 }
 
 abstract type Node {
   Byte tag;
@@ skipping 711 matching lines @@
 
 /* enum BaseClassKind { None, Exact, Subclass, Subtype, } */
 
 type InferredValue {
   ClassReference baseClass; // May be NullReference if kind = None.
   Byte kind; // Index into BaseClassKind.
   Byte valueBits; // See lib/type_propagation/type_propagation.dart
 }
 
 ```