3.2 The EPC Parts

Topic Version2Published11/11/2016
For StandardEPC v1.0

The table below lists the additional parts (in addition to the standard OPC parts) used in an EPC file.

EPC Part

Definition, Purpose, and Requirements

XML data objects

XML data objects defined in any of the Energistics data-exchange standards, such as RESQML, WITSML or PRODML, may be included. In Figure 3-1 , these parts are stored in the resqml and witsml folders.

NOTE: An EPC file may have xml files from multiple versions of the Energistics standards (RESQML, WITSML, and PRODML). For example, an EPC file can contain xml files saved in RESQML v2.0.1 and v2.1.


Any file that is part of an EPC file but stored externally to the EPC file must have an external part reference that points to the external part.

For example, because an HDF5 file is designed for random access (not streaming) and can already compress its data sets, an HDF5 file(s) may be stored outside of an EPC file. However, to accurately maintain all relationships, the package requires use of an external reference to the HDF5 file.

If stored externally to an EPC file, an HDF5 file(s) must:

  • Be referenced in the package through an EPC external part reference part.
  • Have the file extension .h5.

For more information on HDF5 files, see 3.2.3 EPC External Part References and HDF5 Files.

Other types of files

Optionally, other files that contain additional, informal information relevant to the contents of the package, such as these listed below. As a guideline these files are stored in a folder named "media"; for more information, see 3.6 Directory Layout in an EPC File.

  • PDF
  • Video
  • SEGY
  • Images
  • Microsoft Word documents