---
schema_version: "1"
id: ad6dcbf27d06de62f8305092d862edc4f9500ea422196c5728a477c8613ca830
title: Category Cardinality Options
collection: admin
version: current
locale: en-us
portal_url: https://docs.salesforce.com/admin/current/en-us/mktg/264-0-0/mc_pers_catalog_object_cardinality.md
canonical_url: https://help.salesforce.com/s/articleView?id=mktg.mc_pers_catalog_object_cardinality.htm&release=264.0.0&type=5
source_site: help.salesforce.com
content_type: documentation
content_hash: dbbe8da3bbbe4dbc6c9badc149fe38a29019c4e8afe0e810e2145836e6df98eb
description: "Before building your category hierarchy, determine which category cardinality you want to use: one per item or many per item. You choose the cardinality in the Category catalog object. The Category catalog object plays a key role in category assignment and tracking statistics."
products:
  - Marketing
  - Salesforce Personalization
release: "264"
---
# Category Cardinality Options

Before building your category hierarchy, determine which category cardinality you want to use: one per item or many per item. You choose the cardinality in the Category catalog object. The Category catalog object plays a key role in category assignment and tracking statistics.

<table class="slds-table slds-table_bordered slds-max-medium-table_stacked slds-m-bottom_small ">
      <colgroup>
        <col style="width:16.31321370309951%">
        <col style="width:17.128874388254488%">
        <col style="width:66.557911908646%">
      </colgroup>
      <thead class="slds-text-title_caps ">
        <tr class="">
          <th scope="col" class="slds-cell-wrap" style="vertical-align:top;" id="d55222e38">Cardinality Option</th>
          <th scope="col" class="slds-cell-wrap" style="vertical-align:top;" id="d55222e41">Is a category present in an item action event?</th>
          <th scope="col" class="slds-cell-wrap" style="vertical-align:top;" id="d55222e44">Actions</th>
        </tr>
      </thead>
      <tbody>
        <tr class="">
          <td data-label="Cardinality Option" class="slds-cell-wrap" rowspan="2" style="vertical-align:top;" headers="d55222e38 ">One per Item</td>

          <td data-label="Is a category present in an item action event?" class="slds-cell-wrap" style="vertical-align:top;" headers="d55222e41 ">Yes</td>

          <td data-label="Actions" class="slds-cell-wrap" style="vertical-align:top;" headers="d55222e44 ">
            <ul>
              <li>The category is set as the item’s category, replacing existing
                categories. If the event contains more than one category, the first
                category in the list is used.</li>

              <li>Statistics are tracked for the new category.</li>

            </ul>
          </td>

        </tr>
        <tr class="">
          <td data-label="Is a category present in an item action event?" class="slds-cell-wrap" style="vertical-align:top;" headers="d55222e41 ">No</td>

          <td data-label="Actions" class="slds-cell-wrap" style="vertical-align:top;" headers="d55222e44 ">
            <ul>
              <li>No category change occurs.</li>

              <li>Statistics are tracked for the existing categories.</li>

            </ul>
          </td>

        </tr>
        <tr class="">
          <td data-label="Cardinality Option" class="slds-cell-wrap" rowspan="2" style="vertical-align:top;" headers="d55222e38 ">Many per Item (default)</td>

          <td data-label="Is a category present in an item action event?" class="slds-cell-wrap" style="vertical-align:top;" headers="d55222e41 ">Yes</td>

          <td data-label="Actions" class="slds-cell-wrap" style="vertical-align:top;" headers="d55222e44 ">
            <ul>
              <li>The category is added to the item’s set of categories.</li>

              <li>Statistics are tracked only for the added category.</li>

            </ul>
          </td>

        </tr>
        <tr class="">
          <td data-label="Is a category present in an item action event?" class="slds-cell-wrap" style="vertical-align:top;" headers="d55222e41 ">No</td>

          <td data-label="Actions" class="slds-cell-wrap" style="vertical-align:top;" headers="d55222e44 ">
            <ul>
              <li>No category change occurs.</li>

              <li>Statistics aren’t tracked for the existing categories, unless the item
                contains only one category. For example, in a purchase interaction, if an
                item has multiple categories, no category revenue attribution occurs
                because categories can’t be included on purchase line items.</li>

            </ul>
          </td>

        </tr>
      </tbody>
    </table>