The custom ordering of the results. The default ordering is by created_ts descending.
created_ts - The timestamp (ISO 8601) in UTC when the item unit of measure was created.
-created_ts - The timestamp (ISO 8601) in UTC when the item unit of measure was created. (descending)
modified_ts - The timestamp (ISO 8601) in UTC when the item unit of measure was last modified.
-modified_ts - The timestamp (ISO 8601) in UTC when the item unit of measure was last modified. (descending)