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Referencing in GLDF

As described in the chapters on XML hierarchy, the GLDF is structured in a modular way, where parts of the luminaire are defined first and then combined to form Variants. This is done in the XML by referencing the blocks with each other.

Convention

For this purpose, each block, that can be referenced in subsequent blocks, has an id attribute.

ID values can be freely chosen, but must fulfil some restrictions. The most important are

  • Ids must be globally unique. This means that an ID may not be used more than once in the entire GLDF XML.
  • Ids must not contain white spaces.
  • Ids are case sensitive. For example, photometryFile and photometryfile are therefor two different values Ids.
  • We recommend naming Ids in a semantically meaningful way to keep the overview. So instead of e.g. id-1, a better naming would be lightSourceImageFile or emitterEmergencyMode.

The id value of a File element in this example is photometryFile:

<?xml version="1.0" encoding="UTF-8"?>
<Root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="https://gldf.io/xsd/gldf/1.0.0-rc.3/gldf.xsd">
    <Header>
        <!-- Skipped for clarity -->
    </Header>
    <GeneralDefinitions>
        <Files>
            <File id="photometryFile" contentType="ldc/eulumdat" 
                  type="localFileName">SomePhotometry.ldt</File>
        </Files>
    </GeneralDefinitions>
    <ProductDefinitions>
        <!-- Skipped for clarity -->
    </ProductDefinitions>
</Root>

This File can now be referenced in subsequent elements.

Convention

For the purpose of referencing prepreviously defined blocks, subsequent XML node(s) contains XML elements, which ends with ...Reference in their name.

As an example, the following Photometry specification contains an XML element called PhotometryFileReference. Its content must be a previously defined id of a File element. The File itself indicates where the actual photometry file is stored inside the GLDF container.

<?xml version="1.0" encoding="UTF-8"?>
<Root xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="https://gldf.io/xsd/gldf/1.0.0-rc.3/gldf.xsd">
    <Header>
        <!-- Skipped for clarity -->
    </Header>
    <GeneralDefinitions>
        <Files>
            <File id="photometryFile" contentType="ldc/eulumdat" 
                  type="localFileName">SomePhotometry.ldt</File>
        </Files>
        <Photometries>
            <Photometry id="photometry">
                <PhotometryFileReference fileId="photometryFile"/>
            </Photometry>
        </Photometries>
        <!-- Skipped for clarity -->
    </GeneralDefinitions>
    <ProductDefinitions>
        <!-- Skipped for clarity -->
    </ProductDefinitions>
</Root>