This folder are intended to store the lists of prefixes (LOP).
Each LOP should be a file in the form NAMEOFTHELIST.set.php and must contain
only the declaration of the $sci_list array:
where the exp_i eth index should be an integer, and each sub-array of the
$sci_list should be an array of the list of equivalent forms of the prefix
(i.e., with html signs: µ,μ,μ, ...)
See the LOP "si_short_html" to get a better example.
The preferred/single prefix should starting the array, on the 0 index.
Then, Avoid alphabetic/negative index if you only will use a single prefix.
If you need to add a spacer between the number and the prefix (dash,space,...), specify it
when creating a new object trough the constructor, not in the LOP.
Never forget the exp 0 assigned with '', unless you don't need it
(i.e.: when you want mass results in Kg). To get a better view, feel free to see the other
files of this folder.
All the files on this folder could have the 400 permissions or similar (440,444)
And this folder could have the permission 500, or similar (550,555)