Understanding SSA DI Numbers when starting your disability claim can be your secret weapon. These unique identifiers are mapped within the Program Operations Manual System (POMS) and cross-referenced with the SSA Blue Book, making it easier to locate critical information about your condition's eligibility. In this guide, we break down what DI Numbers are, how they're assigned, and how you can use them—alongside Blue Book listings and Compassionate Allowances—to strengthen your SSDI application and speed up the process.