A vowel counting system. Base n, where n is the number of distinct vowels in the alphabet. In this case, there are 5 vowels. A number is made of the digits that are interspersed with place-holder consonants, whose sequences are undefined (ranging from being random to spelling out the names of those numbers in that language -- these latter names may have to be neologisms).
In this case:
A E I O U 1 2 3 0 4
Therefore it is equivalent to a base 5. Except that it is easy to read out loud.
It is reasonably-general. :o)