Short answer:

Every weekday morning the system checks all items that have been recently added or edited and makes suggestions as to whether to buy new or additional copies of these books. The number of copies suggested for purchase is based on a ratio of the student numbers (usually 1 copy per 20 students). However this number is amended downwards based upon the current level of library stock (including alternate editions), borrowing activity and available budget.

Long answer:

Step-by-step guide to how it works

1. Identify items to check (e.g. recently edited items)
2. Validate ISBNs
3. Drop items that are already on order – Recently added step
4. Estimate initial copies required based on item importance (e.g. core, additional) and student numbers
5. Drop books which have sufficient copies instock according to Aleph
6. Find costs (from Aleph, Amazon, GoogleBooks,etc.)
7. Discard books without available prices
8. Get recent loan information from Aleph
9. Drop underused items
10. Identify latest edition of books
11. Round robin purchasing algorithm to keep purchasing suggestions within Aleph budget
12. Output results