A glide is i or u when followed by a nucleus and not followed by abother glide.
A diphthong is one of ai, au, ei, oi not followed by a glide.
A vowel is one of a, e, i, o, u not followed by a nucleus.
a is any number of commas (possibly none) and the character 'a' or 'A'.
e is any number of commas (possibly none) and the character 'e' or 'E'.
i is any number of commas (possibly none) and the character 'i' or 'I'.
o is any number of commas (possibly none) and the character 'o' or 'O'.
u is any number of commas (possibly none) and the character 'u' or 'U'.
y is any number of commas (possibly none) and the character 'y' or 'Y'.