The product’s content inventory will be displayed in the completed HPD following the Format specified in the HPD Open Standard version 2.1, according to which of the three content inventory data entry methods was chosen in creating the HPD.  If the HPD is created using the HPD Builder 2.1 tool, the correct display of the data will be automatically selected.  If the HPD is created manually, it will be up to the creator to select the appropriate of content inventory format for displaying the data in preparing their HPD, using the formats that are included in HPD Open Standard 2.1 document.

HPD 2.1 has three approaches for creating an HPD, they are:

Nested Materials Inventory with Material-level thresholds.  This is the approach used in HPD 2.0 in which contents are reported first at the materials level and substances are then itemized within each material.  Thresholds are established for each separate material and these thresholds determine which substances must be listed under each material.

Nested Materials Inventory with Product-level threshold.  This is similar to the first approach in that contents are reported first at the materials level and then substances are itemized within each material.  In this approach, a single threshold is established for the entire product and this threshold is used to determine which substances must be listed for any of the materials.

Basic Inventory with Product-level threshold.  This approach does not identify materials and creates a single list of all substances in the product.  It uses a single threshold for the entire product.

Nested materials inventories often are most appropriate for complex assemblies with many component parts.  In many cases, the HPD can be created from data provided by suppliers for their materials  For product lines with many variations, the nested approach can be most efficient, since individual materials can be switched and replaced more easily to reflect differences in color, fabric covering, etc.