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 class javax.xml.transform.OutputKeys
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: javax.xml.transform.OutputKeys
  super_class: java.lang.Object
{
  public static final java.lang.String METHOD;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "method"

  public static final java.lang.String VERSION;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "version"

  public static final java.lang.String ENCODING;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "encoding"

  public static final java.lang.String OMIT_XML_DECLARATION;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "omit-xml-declaration"

  public static final java.lang.String STANDALONE;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "standalone"

  public static final java.lang.String DOCTYPE_PUBLIC;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "doctype-public"

  public static final java.lang.String DOCTYPE_SYSTEM;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "doctype-system"

  public static final java.lang.String CDATA_SECTION_ELEMENTS;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "cdata-section-elements"

  public static final java.lang.String INDENT;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "indent"

  public static final java.lang.String MEDIA_TYPE;
    descriptor: Ljava/lang/String;
    flags: (0x0019) ACC_PUBLIC, ACC_STATIC, ACC_FINAL
    ConstantValue: "media-type"

  private void <init>();
    descriptor: ()V
    flags: (0x0002) ACC_PRIVATE
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // javax.xml.transform.OutputKeys this
         0: .line 37
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // javax.xml.transform.OutputKeys this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Ljavax/xml/transform/OutputKeys;
}
SourceFile: "OutputKeys.java"