Enrichment Activity

The Enrichment activity allows four links:

In the fourth option (a link):

Link definition: Allows the selection of the type of link and the target of the link. Link type includes:

1. Define a collection (1-N relationship)
2. Define a link whose target is always available (1-1 relationship). The join conditions must be defined by a single record in the target table.
3. Define a link whose target may not exist in the database (0-1 relationship).
4. Define a link by searching for a reference among several options (1-1 or 1-N relationship).
   

Question:

Does each link definition establish a SQL right join from the filtering dimension (table) to the target table?

Or, does it establish a SQL right join except the third option:

"3. Define a link whose target may not exist in the database (0-1 relationship)). The join condition must be defined by 0 or 1 (max.) record in the target table."

...which sounds like it establishes a left join.

Thanks.