Diy vs Dy - Dipthong and Other Unique Letter Combinations

@YoSoyYossarian Magandang araw po sa inyo! I hope you're safe in the middle of everything.Firstly, could you clarify what you mean by "diy-" as a prefix? Since I don't believe there is such a "prefix."Secondly, unfortunately this is a matter of orthography, and Tagalog orthography itself has been subject to numerous changes over the last few years. I believe that the current standards are laid out in the "Manwal sa Masinop na Pagsulat" ("Manual to Neat Writing") by the Komisyon sa Wikang Filipino (Commission on the Filipino Language or KWF). Unfortunately, while the book is free to download on their website, it's written entirely in Tagalog or "Filipino," and I know of no English translations, so if ever you may have to consult with someone else to translate it for you.For the meantime, it will really just be memorization, but thankfully, in informal Tagalog (and sometimes even in formal Tagalog style guides), words that use the "diy" diphthong can be spelled as "dy" as an accepted variation, so I suggest spelling it as "dy" if you're not certain of the standard spelling, since it's accepted anyways.If you have any questions, please feel free to ask!

@AngTaongsiClyde Magandang araw rin sayo! Hope you are safe as well! Thank you so much for responding to my questions!Below is a photo from the "Dipthong and Other Unique Letter Combinations" lesson. It shows "diy" and "dy" as being equivalently pronounced prefixes for words. An example of a diy word given is "diyaryo", while a word with "dy" example is "dyipni".The issue for me has been the drill for this lesson (see below photo). It's a cool exercise, it shows us an incomplete word, has audio of someone speaking the compete word, and we have to write out the full word including the missing dipthong/letter combination. The problem is that it marks me wrong if I put "diy" where a "dy" should be and vice versa, even though they sound exactly the same and I haven't been asked in the lessons yet to memorize spelling of words. In the photo I attached, I accidentally wrote "dyaryo" instead of "diyaryo" based on the sound.From your response, it seems like if I wrote "dyaryo" instead of "diyaryo" in an informal context, everyone would understand what I meant and it would be okay. Or is it truly wrong to spell it "dyaryo"? For the purpose of these drills, I will do as you suggested and just memorize the spelling. I just want to confirm if "dyaryo" is truly an acceptable spelling.

@YoSoyYossarian You have a good point. I've updated the drill to accept both answers.
-For certain words, there is definitely a "preferred" version. It's almost always "dyip" and not "diyip", for example. "Diyan" and "siya" are more appropriate in formal settings. There's no good rule that I've found, it just comes down to memorizing which is more common for which word.@AngTaongsiClyde gives good advice here, though.

This is one of the few instances of "deep" orthography in Tagalog. Tagalog has fairly "shallow" orthography. Diy vs dy is a matter of historical pronunciation. The <i> in between the <d> and the <y> has been lost in modern Tagalog (in most speakers, rural speakers may retain the distinction). Resulting in the diyaryo (dee yar yo) being pronounced dyaryo (dja ryo). In general if the preferred spelling is <dy> and not <diy> one can assume the original letter was probably originally a sound similar to <j> in in English. Jack en Poy (from Japanese Jankenpon) Jacket, Jeep etc.Similar sound changes (loss of <i> medially and the resulting palatalization of the proceeding consonants) has happened with <tiy> and <siy> as well.Tiyan -> tyan (chan) historically "tee yan"
Siya -> sya (sha) historically "see ya"Another sound change that makes tagalog orthography deep is the smoothing of the <ay> dipthong. Aywan is now <ewan> in modern Tagalog.
Similarly, loss of the glottal stop and the resulting diphthong which is then smoothed produces some very divergent pronunciations. Kailan "kaQ eelan" or kâ ilan(Q and ^ represent the glottal stop) progressed to "kaylan" (dipthong) which was later smoothed to bring us "kelan".Other sound changes have happened too but only nerds care about them The ^ in words is disappearing pô -> pō (long vowel), and <ts> has changed from [ts] to [t͡ʃ] in most urban and younger speakers, where at one point it really did sound like the <ts> sound in bats. For more reading on orthographic depth: en.wikipedia.org/wik i/Orthographic_depth

That's right! Diy / Dy is pronounced like / j / and the spelling in Tagalog is also evolving which results in shortening the spelling of Diy to dy for example: diyan /jan/ before is now spelt dyan / jan /; diyaryo / jar-yo/ = dyaryo / jar-yo but siya /sha/ , Diyos /jos / are still spelt with the i before the y. Contemporary writings especially the conversational one would spell it DY but the formal writings would spell it DIY.