[meteorite-list] The 100th Bulletin Now Out

[Thunder Stone]

List:
 
I was looking a the lastest submissions in the Bulletin and noticed some OC's in the 100th Bulletin with the class:
H~6, H~5, L~5... and so on.  Apperently the "tilde symbol" means that the meteorite has an "approximate petrologic type."
So, what is the diiference between H5, H approximately 5, H 4-6, and H 4/6?
 
Seems a little odd to me, but maybe there is an important reason for it.
 
Greg S