ITERM$

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ITERM$

System variable:  ITERM$  
Length:  3  
Description:  The system variable named ITERM$ contains the identification number of the initiating terminal for the current program. 
This value is a three-byte string in the form "Tnn", where "nn" is a value from "00" to "99". 
When a program is running in a foreground partition, the value of ITERM$ is identical to TERM$. However, for a program running in a background partition, 
TERM$ will contain a null value and ITERM$ will contain the identification number of the terminal initiating the background process.