either and neither

X-SAMPA is generally based on the IPA which in turn is based in a large part on the Latin alphabet taking into account how it's used in modern languages. Romanisation of foreign languages tends naturally to be based on similar things. This "long I" is a diphthong (except, maybe if you're from southern US) The starting point is around [A] & [6] and the ending point is around [I] & [e]. This is why it's written [AI], [Ae], etc. in X-SAMPA.

>>X-SAMPA is generally based on the IPA which in turn is based in a large part on the Latin alphabet taking into account how it's used in modern languages. Romanisation of foreign languages tends naturally to be based on similar things. This "long I" is a diphthong (except, maybe if you're from southern US) The starting point is around [A] & [6] and the ending point is around [I] & [e]. This is why it's written [AI], [Ae], etc. in X-SAMPA.<<

In most North American English dialects the starting point is [a] rather than [A] or [6], except where Canadian Raising applies, where then it is more like somewhere ranging from [6] to [@] to [V].

Good point, okay the starting point is somewhere around the area of [a, A, V, @]. Of course, in AusE it has to start off pretty back so as not to get confused with our "long A" i.e. /{I/.

<<I'm sorry if I confused you, but my native language is portuguese and I instinctively used "AI" to represent an open A, as in the spanish sentence "AI caramba!" or the word "TAIpei" (capital of TAIwan). >>

That was how I took it, as well.

And you're probably familiar with D being pronounced something like the TH in "neither" as well, since that occurs in Spanish and Portuguese, as in "Alfredo" and "fado", which explains why you were using that in your original example.