+typedef enum UnitType UnitType;
+typedef enum UnitLoadState UnitLoadState;
+typedef enum UnitDependency UnitDependency;
+
+enum UnitType {
+ UNIT_SERVICE = 0,
+ UNIT_SOCKET,
+ UNIT_BUSNAME,
+ UNIT_TARGET,
+ UNIT_SNAPSHOT,
+ UNIT_DEVICE,
+ UNIT_MOUNT,
+ UNIT_AUTOMOUNT,
+ UNIT_SWAP,
+ UNIT_TIMER,
+ UNIT_PATH,
+ UNIT_SLICE,
+ UNIT_SCOPE,
+ _UNIT_TYPE_MAX,
+ _UNIT_TYPE_INVALID = -1
+};
+
+enum UnitLoadState {
+ UNIT_STUB = 0,
+ UNIT_LOADED,
+ UNIT_NOT_FOUND,
+ UNIT_ERROR,
+ UNIT_MERGED,
+ UNIT_MASKED,
+ _UNIT_LOAD_STATE_MAX,
+ _UNIT_LOAD_STATE_INVALID = -1
+};
+
+enum UnitDependency {
+ /* Positive dependencies */
+ UNIT_REQUIRES,
+ UNIT_REQUIRES_OVERRIDABLE,
+ UNIT_REQUISITE,
+ UNIT_REQUISITE_OVERRIDABLE,
+ UNIT_WANTS,
+ UNIT_BINDS_TO,
+ UNIT_PART_OF,
+
+ /* Inverse of the above */
+ UNIT_REQUIRED_BY, /* inverse of 'requires' and 'requisite' is 'required_by' */
+ UNIT_REQUIRED_BY_OVERRIDABLE, /* inverse of 'requires_overridable' and 'requisite_overridable' is 'soft_required_by' */
+ UNIT_WANTED_BY, /* inverse of 'wants' */
+ UNIT_BOUND_BY, /* inverse of 'binds_to' */
+ UNIT_CONSISTS_OF, /* inverse of 'part_of' */
+
+ /* Negative dependencies */
+ UNIT_CONFLICTS, /* inverse of 'conflicts' is 'conflicted_by' */
+ UNIT_CONFLICTED_BY,
+
+ /* Order */
+ UNIT_BEFORE, /* inverse of 'before' is 'after' and vice versa */
+ UNIT_AFTER,
+
+ /* On Failure */
+ UNIT_ON_FAILURE,
+
+ /* Triggers (i.e. a socket triggers a service) */
+ UNIT_TRIGGERS,
+ UNIT_TRIGGERED_BY,
+
+ /* Propagate reloads */
+ UNIT_PROPAGATES_RELOAD_TO,
+ UNIT_RELOAD_PROPAGATED_FROM,
+
+ /* Joins namespace of */
+ UNIT_JOINS_NAMESPACE_OF,
+
+ /* Reference information for GC logic */
+ UNIT_REFERENCES, /* Inverse of 'references' is 'referenced_by' */
+ UNIT_REFERENCED_BY,
+
+ _UNIT_DEPENDENCY_MAX,
+ _UNIT_DEPENDENCY_INVALID = -1
+};
+
+const char *unit_type_to_string(UnitType i) _const_;
+UnitType unit_type_from_string(const char *s) _pure_;
+
+const char *unit_load_state_to_string(UnitLoadState i) _const_;
+UnitLoadState unit_load_state_from_string(const char *s) _pure_;
+