http://xml.apache.org/commons/components/external/: xml-commons provides an Apache-hosted set of DOM, SAX, and JAXP interfaces for use in other xml-based projects. Our hope is that we can standardize on both a common version and packaging scheme for these critical XML standards interfaces to make the lives of both our developers and users easier. The External Components portion of xml-commons contains interfaces that are defined by external standards organizations. For DOM, that's the W3C; for SAX it's David Megginson and sax.sourceforge.net; for JAXP it's Sun. 
public final class javax.xml.datatype.DatatypeConstants$Field
  minor version: 0
  major version: 59
  flags: flags: (0x0031) ACC_PUBLIC, ACC_FINAL, ACC_SUPER
  this_class: javax.xml.datatype.DatatypeConstants$Field
  super_class: java.lang.Object
{
  private final java.lang.String str;
    descriptor: Ljava/lang/String;
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private final int id;
    descriptor: I
    flags: (0x0012) ACC_PRIVATE, ACC_FINAL

  private void <init>(java.lang.String, int);
    descriptor: (Ljava/lang/String;I)V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=2, locals=3, args_size=3
        start local 0 // javax.xml.datatype.DatatypeConstants$Field this
        start local 1 // java.lang.String str
        start local 2 // int id
         0: .line 179
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
         1: .line 180
            aload 0 /* this */
            aload 1 /* str */
            putfield javax.xml.datatype.DatatypeConstants$Field.str:Ljava/lang/String;
         2: .line 181
            aload 0 /* this */
            iload 2 /* id */
            putfield javax.xml.datatype.DatatypeConstants$Field.id:I
         3: .line 182
            return
        end local 2 // int id
        end local 1 // java.lang.String str
        end local 0 // javax.xml.datatype.DatatypeConstants$Field this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    4     0  this  Ljavax/xml/datatype/DatatypeConstants$Field;
            0    4     1   str  Ljava/lang/String;
            0    4     2    id  I
    MethodParameters:
      Name  Flags
      str   final
      id    final

  public java.lang.String toString();
    descriptor: ()Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // javax.xml.datatype.DatatypeConstants$Field this
         0: .line 191
            aload 0 /* this */
            getfield javax.xml.datatype.DatatypeConstants$Field.str:Ljava/lang/String;
            areturn
        end local 0 // javax.xml.datatype.DatatypeConstants$Field this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Ljavax/xml/datatype/DatatypeConstants$Field;

  public int getId();
    descriptor: ()I
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // javax.xml.datatype.DatatypeConstants$Field this
         0: .line 199
            aload 0 /* this */
            getfield javax.xml.datatype.DatatypeConstants$Field.id:I
            ireturn
        end local 0 // javax.xml.datatype.DatatypeConstants$Field this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Ljavax/xml/datatype/DatatypeConstants$Field;
}
SourceFile: "DatatypeConstants.java"
NestHost: javax.xml.datatype.DatatypeConstants
InnerClasses:
  public final Field = javax.xml.datatype.DatatypeConstants$Field of javax.xml.datatype.DatatypeConstants