Hello everyone and first of all congratulations for this great forum.

I am new user and even though I read many, many threads in this forum, and others across the internet, I still don’t understand some terms regarding my smartphone.

I have model A510F and here are my current firmware:

1.I understand that CP is modem firmware, so, what is the difference between PDA(AP) and CSC firmware? Why do we need CSC since AP decides firmware updates? Are the country codes 2 digit or 3 digit? What information do I get from these 3 codes? (XXU vs OXA?)

2.Using the app Phone Info I found that product code is SM2A510FZDAXEO. I believe XEO is from Poland which is true, because even though I bought the phone here in Greece, the seller imported it from Poland. So, overall, now we have XXU / OXA / ZDA. How are these connected?

3.Is it generally a good idea to change the CSC to EUR, which is Greece, since I live here or shall I leave it as it is? Do I benefit from something?

4. Both EUR and XEO are unbranded codes. I see that in EUR latest android is version 7 but for XEO is 6. So….what makes it such difference? I mean, since they are not carrier dependent who is stalling/deciding the upgrade to v.7 in Poland?

I am really sorry if those questions sound noob to you but I would really appreciate it if someone had the time to reply and explain or post a link for me to further study.

Thank you in advance.