"N" ~ New.

"A" ~ Condition is 25% off retail price.   New or near new.

"B" ~ Condition is 50% off retail price. Cover may be worn or written on.  Spine may be ripped or taped. May not be current edition

"C" ~ Condition 1-10 pages may be missing or written on. Cover may be gone or very ripped. Useable.  May not be current edition

"NC" ~ Means that it is not current or compatable with the most recent edition.