"i-" verb question

I- verbs beginning with H, L, R, W, and Y have the form like you mentioned.
Also, I- verbs with the roots beginning with vowels have that kind of format.
I think that should be all the irregular forms, though.

@TLDCAdmin Thank you! I spent a couple of hours researching through dictionaries and deduced the conclusion that you just verified. I had posed the question originally because I was incorrectly answering "i- verb" flashcards and couldn't figure out why. Turns out it was the H, L, R, W, Y and vowel cards I was messing up on, trying to put infixes where there should have been prefixes. I fully expect to ace these cards from now on! Thank you again!

@Diegocorry I was not even conscious of the difference until now. The set of letters given by TLDCAdmin seem to be correct, however, I think that for some words they are not strictly followed.For example, right now I can think of having heard both:ihinulog and inihulog (to let something drop)
ihinanda and inihanda (to prepare something)
ihinatid and inihatid (to deliver something) - is this the word you meant for "inihatad"?
iwinaldas and iniwaldas (to squander something)You can also add root words that begin with a vowel.alisin - inalis
inumin - ininom
iwanan - iniwan
utangin - inutang

@Tagamanila Yes, I’ve observed that the convention is not hard and fast, especially with words having initial “h”.

I have been told by natives that roots beginning l, r, w, y usually follow this exception, but h usually doesn't. And this applies not only to i-verbs but in-verbs

@leosmith @Tagamanila I did a little bit of searching through our TextSearch tool here.
It looks like newspaper articles (formal writing) tend toward the "ini" prefix for roots beginning with "H". Of course spoken/casual language is often quite different, I know!Ex:
Searching newspaper articles only...instance counts:inihatid = 99
ihinatid = 1
====
inihanda = 325
ihinanda = 2
====
iniharap = 191
ihinarap = 1

I don't doubt that. I specifically asked for colloquial usage, which may account for that answer. But I will take a poll to verify.