Arguably the most influential factor shaping this new class was the competitive nature of scholarly candidates entering civil service through the imperial examinations. Although not all scholar-officials came from the landholding class, sons of prominent landholders had better access to higher education, and thus greater ability to pass examinations for government service. Gaining a scholarly degree by passing prefectural, circuit-level, or palace exams in the Song period was the most important prerequisite in being considered for appointment, especially to higher posts; this was a departure from the Tang period, when the examination system was enacted on a much smaller scale. A higher degree attained through the three levels of examinations meant a greater chance of obtaining higher offices in government. Not only did this ensure a higher salary, but also greater social prestige, visibly distinguished by dress. This institutionalized distinction of scholar-officials by dress included the type and even color of traditional silken robes, hats, and girdles, demarcating that scholar-official's level of administrative authority. This rigid code of dress was especially enforced during the beginning of the dynasty, although the prestigious clothing color of purple slowly began to diffuse through the ranks of middle and low grade officials.