OpenAtlas uses several shortcuts in order to simplify connections between entities that are always used the same way.
These shortcuts are named OA + the respective number. Currently OpenAtlas uses 3 shortcuts:

OA7 "has relationship to"

OA7 is used to link two Actors (E39) via a certain relationship
E39 Actor linked with E39 Actor
E39 (Actor) - P11i (participated in) - E5 (Event) - P11 (had participant) - E39 (Actor)

Example: [ Stefan (E21)] participated in [ Relationship from Stefan to Joachim (E5)] had participant [Joachim (E21)]

The connecting event is defined by an entity of class E55 (Type):
[Relationship from Stefan to Joachim (E5)] has type [Son to Father (E55)]

OA8 "appears for the first time in"

OA8 is used to link the beginning of a persistent item's (E77) life span (or time of usage) with a certain place. E.g to document the birthplace of a person.
E77 Persistent Item linked with a E53 Place:
E77 (Persistent Item) - P92i (was brought into existence by) - E63 (Beginning of Existence) - P7 (took place at) - E53 (Place)

Example: [Albert Einstein (E21)] was brought into existence by [Birth of Albert Einstein (E12)] took place at [Ulm (E53)]
.

OA9 "appears for the last time in"

OA9 is used to link the end of a persistent item's (E77) life span (or time of usage) with a certain place. E.g to document a person's place of death.
E77 Persistent Item linked with a E53 Place:
E77 (Persistent Item) - P93i (was taken out of existence by) - E64 (End of Existence) - P7 (took place at) - E53 (Place)

Example: [Albert Einstein (E21)] was taken out of by [Death of Albert Einstein (E12)] took place at [Princeton (E53)]