Enchi is a co-dominant mutation (some will say incomplete dominant, which may be more correct but hardly anybody uses that term) It's a subtle mutation This link shows a few examples; Enchi. Possible het hypo means that it has the possibility of carrying the hypomelanistic mutation which is a recessive trait. Here is a link to some examples of hypomelanistic. Yellowbelly is another subtle mutation also known as het Ivory which is another co-dominant mutation, here are some yellowbelly examples.
If you breed the Enchi possible het hypo to a yellowbelly, you will get; enchi's, yellowbellies, normals, and enchi yellowbellies all of which will be possible het hypo.