| Object | Group | Definition | Explanatory Text | Link to GSIM |
| HierarchicalCodelist | Hierarchical Code List | Organised collection of codes that may be part of many parent/child relationships with other codes in the scheme, as defined by one or more hierarchies of the scheme. | The Code List in SDMX can be hierarchical but it is capable of being processed as flat list as each Code can have only one parent code. A Hierarchical Code List (HCL) is able to have multiple hierarchies and can have formal Levels. The Codes used in an HCL are derived from one or more Code Lists therefore an HCL can combine Codes from multiple Code Lists and define hierarchies from these Codes. For example, adding geographic codes such as continents or regions. | Statistical Classification |