a - approved. Your contribution has been already checked by UG Editor and accepted into archive. It gives you a direct link to the contribution.

w - waiting. We recieved your contribution, however it was not checked for accuracy and quality yet.

d - denied. Contribution has been rejecteds by our Editor. You are not allowed to re-submit it.

d * - denied. Editor rejected your contribution and left a message for you, it is allowed to re-submit it. Most likely this happened because you have some accuracy flaws in your contribution. Move your cursor over the name of your contribution and you will read a message from Editor. By clicking on that link you will be redirected to the page with all fields filled with your data.

From the FAQ

No idea what S means.
Populus vult decipi. Decipiatur.

Quote by Mistress_Ibanez
It's can be a contraction and genitive case.

Quote by Mistress_Ibanez
If you cut down on these costs students won't learn so well, effecting the "quality"...