Final answer:
Soldiers must complete specific Structured Self-Development (SSD) levels before attending each tier of the Noncommissioned Officer Education System (NCOES) - SSD1 before BLC, SSD2 before ALC, SSD3 before SLC, and SSD4 before the SMA.
Step-by-step explanation:
The Structured Self-Development (SSD) levels required prior to attendance at the Noncommissioned Officer Education System (NCOES) vary depending on the level of leadership responsibility within the U.S. Army. Before attending the Basic Leader Course (BLC), the soldier needs to complete SSD Level 1. The Advanced Leader Course (ALC) requires completion of SSD Level 2, and the Senior Leader Course (SLC) mandates SSD Level 3 completion beforehand. Lastly, the Sergeant Major Academy (SMA) requires the SSD Level 4 completion prior to attendance. Each SSD level is designed to provide enlisted soldiers with the knowledge and skills necessary to perform in specific leadership roles.