How add or save listing property works?

This is only for very advanced developers who want to change some core features! Not for regular users!
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Also check some articles in knowledge base like: http://iwinter.com.hr/support/?p=1288

So usually estate_m.php (method save) and controller estate.php method edit

Basic field details are defined in:

Screenshot_2

affected fields here:

Screenshot_3

Saving process:

Screenshot_1