As previously mentioned, in 1374, the Ming government banned all religions other than Buddhism and Taoism. This was good for Taoism as it meant that it could continue to exist above ground, but this also brought with it much government regulation. That same year, an examination system was introduced, whereby would-be priests had to sit an exam in the capital that was held once every three years, with only those with sufficient knowledge of Taoist classics and who passed being licensed by the government as official priests. Upon passing, the new official priests would qualify to receive a "dudie" (度牒, dù dié) clerical certificate, a sort of official state license for priests.