Answered: What is "updatetype" in table "qa_posts"

Welcome Midriaz!

Fortunately, the answer is in the code.

Its meaning, from qa-include/db/install.php:207:

'updatetype' => 'CHAR(1) CHARACTER SET ascii', // what was done to this part - see /qa-include/app/updates.php

Its possible values, from qa-include/app/updates.php:37:

// Character codes for the different types of updates on a post (updatetype columns)

define('QA_UPDATE_CATEGORY', 'A'); // questions only, category changed

define('QA_UPDATE_CLOSED', 'C'); // questions only, closed or reopened
define('QA_UPDATE_CONTENT', 'E'); // title or content edited
define('QA_UPDATE_PARENT', 'M'); // e.g. comment moved when converting its parent answer to a comment
define('QA_UPDATE_SELECTED', 'S'); // answers only, removed if unselected
define('QA_UPDATE_TAGS', 'T'); // questions only
define('QA_UPDATE_TYPE', 'Y'); // e.g. answer to comment
define('QA_UPDATE_VISIBLE', 'H'); // hidden or reshown

I hope you find this information helpful.