How to interpret the "instance" in a ArcCatalog connection?

Question

I'm using ArcGIS 10.2.1.  I have created a connection in Arc Catalog to an Oracle geodatabase.  In the text box for the "instance" I put in "ddev1_linux".  When I examine the connection properties, I see that it is set to "sde:oracle11g:ddev1_linux;LOCAL=gisdta".  I'm curious why the LOCAL=gisdta has been appended.  How do I interpret the "instance" string in the connection properties?

Asrujit_SenGupta · Accepted Answer

Connect to Oracle from ArcGIS—Help | ArcGIS Desktop  This link provides all the details, regarding what can be provided in the 'Instance'parameter depending on the different scenarios.

I personally have never observed the 'LOCAL' part getting appended after making a connection. The addition of the "sde:oracle11g" is as expected and as designed.

How To: Install ArcSDE on a machine that is remote from the Oracle RDBMS

The above link mentions the below:

Note:
TWO_TASK (for UNIX/Linux) and LOCAL (for Windows) are Oracle environment variables.
Refer to Oracle documentation for further information.

Yet another DBA blog: Using "LOCAL" environment variable