The following example creates and registers a conditional event named plugin.magento.catalog.model.resource_model.product.save_low_stock_event. Its parent is plugin.magento.catalog.model.resource_model.product.save. It defines rules that trigger when all of the conditions are true:

• The value of qty is less than 20
• The category_id is either 3, 4, or 5
• The product name contains TV
• The store_id of product category is either 1 or 2
• The application area is adminhtml
• The quantity_and_stock_status.qty value has changed

These fields are present and declared in the parent event.