Hi @asaatifshahab and thanks for your query. The Tobii TX300 is part of the Tobii Pro business department.
This forum is intended for support with the Tobii Tech Consumer level eye trackers (4C, Eyex, etc) and their associated SDK’s.
We would advise that you get in touch with Tobii Pro Support team directly @ http://www.tobiipro.com/contact/contact-support/ for an
answer to your query.
However, that being said, I found online a reference for the ADCSpx co-ordinate system on the Tobii Pro Studio Manual (Page 136)
https://www.tobiipro.com/siteassets/tobii-pro/user-manuals/tobii-pro-studio-user-manual.pdf
Which also demonstrates pictorially the co-ordinate system in question. Hopefully this answer your query.