| Attributes |
| Signature | Optionality | Multiplicity | Constant | Documentation |
 action_archetype_id : String | 1 | -- | | Perl-compliant regular expression pattern, enclosed in ‘//’ delimiters, indicating the valid archetype identifiers of archetypes for Actions corresponding to this Activity specification. Defaults to “/.*/”, meaning any archetype. |
| decription : ITEM_STRUCTURE | 1 | -- | | Description of the activity, in the form of an archetyped structure. |
| timing : DV_PARSABLE | 1 | -- | | Timing of the activity, in the form of a parsable string, such as an HL7 GTS or ISO8601 string. |