It's a referenced element. For detailed description, please refer referenced element doc. Fulfillment order pick update/modification detailed information Fulfillment order pick identifier Collection of pick line items representing modified information Collection of custom attributes to be updated for the fulfillment order pick. Fulfillment order pick update/modification line item information. Pick line item identifier Quantity in standard unit of measure. Collection of pick substitute line items representing modified information Fulfillment order pick update/modification substitute line item information SKU number Quantity in standard unit of measure. This type can hold a string of max length of 25 characters. This type can hold a number of digits count 12. This type can hold a number of digits count 20 and fraction digit count of 4.