Where to define third party logical system name in file to idoc scenario

Hi Friends,

I am shalini shah.

I have one doubt, where I can define the logical system name in File to Idoc scenario.

I created Logical system for R/3 system in SALE t.code, but where to define the Third party logical system ,

In SALE or any where.

Please give me solution.

Warm Regards,

Shalini Shah