{oj} - what does this mean? -Understanding the use of curly braces and "OJ"

ODBC supports the SQL-92 left, right, and full outer join syntax. The escape sequence for outer joins is

{oj outer-join}

where outer-join is

table-reference {LEFT | RIGHT | FULL} OUTER JOIN {table-reference | outer-join} ON search-condition

table-reference specifies a table name, and search-condition specifies the join condition between the table-references.

An outer join request must appear after the FROM keyword and before the WHERE clause (if one exists). For complete syntax 

https://docs.microsoft.com/en-us/sql/odbc/reference/develop-app/outer-joins?view=sql-server-2017