I've already seen the questions Do I need a degree in IT to apply for an EU Blue Card as a software engineer or is any degree enough? and What's my degree worth in Germany?. Both answers state that you'd have to get your degree recognized in order to work as a software engineer in Germany.
However, on DAAD's website, there's a document (page 5) stating that for "IT specialists" and "language teachers", there's no need for any degree at all:
For jobs requiring qualified professional training, approval may be issued for qualified workers with a recognised degree or a foreign university degree equivalent to a German university degree (Section 27 No. 1 Employment Regulation), to IT specialists (Section 27 No. 2 Employment Regulation) or language teachers (Section 26 Employment Regulation).
Also, in the question Blue Card vs Regular Work Permit for IT Specialists, the OP states he already works as an "IT specialist" on a regular work permit in Germany but doesn't have any degree. So I'm quite confused.
One explanation I've come up with is that to apply for a Blue Card you do still need a degree, while to apply for a regular German work permit you don't need a degree. I'm not sure if such an interpretation of the above information makes much sense.
Also, I'm not sure what the term "IT specialist" exactly means. It seems that any software engineer should classify but I can't find the place where an exact definition is given.