http://www.wfmc.org/2008/XPDL2.1

elements
Author
BasicType
Codepage
CostUnit
Countrykey
Created
DataType
DeclaredType
Description
Documentation
ExtendedAttribute
ExtendedAttributes
ExternalPackage
ExternalPackages
ExternalReference
FormalParameter
FormalParameters
Loop
LoopMultiInstance
LoopStandard
PackageHeader
PriorityUnit
RedefinableHeader
Responsible
Responsibles
SchemaType
Script
TypeDeclaration
TypeDeclarations
Vendor
Version
XPDLVersion

complexTypes
ExpressionType
Extensible
XpdlType

groups
DataTypes