What does ".." mean in "SELECT * FROM database..table"?

I understand than in the SQL statement that the part xxx

, say xxx.TableName

, refers to the schema of the data table. Typically, most tables are created as dbo.TableName

. When referencing a table in SQL code, the default schema can be omitted and you can simply refer to the table by the table name. Likewise, if you need to refer to a table in another database, you can refer to it with the following syntax Database.dbo.TableName

.

However, I just ran into a different user code that has Database..TableName

. What does it mean ..

? I can accept a reasonable answer, but I cannot find any specific documentation. (Google doesn't seem to work with double dot text.)