Share Mode (Magic xpa 3.x)
In addition to the Access mode, every process must declare a Share mode. The Share mode specifies which Access modes are allowed by other processes to access this data source.
For example, a statistical program would access a table in Access mode=R and Share mode=W. Therefore, it would only read records from the table and would allow any other process that is also only reading records from the table to access it at the same time. On the other hand, a program may need to update some data for all the records, so it wants to block all other processes for updating the data, but still allow processes to see the data, therefore, Share mode=R is required.
To open a data source in an exclusive mode, the Share mode is set to N for None. No other process may be granted access to the data source.