What does the Double Period Mean in T-SQL Script?

When a double period is used, as in:

ExactMAXSampleDB..Part_Master

This means the schema is inferred to be the default schema of the current login.

In most cases this will be .dbo. So instead of having to provide it one could use the shortcut of the “..” or more correctly the default for that user which is more right due to the fact that the author of the script may not know which default is in use but may know the table and databases name that may well be standard as determined by the software app deployed.