to the New Economic Zones (NEZs), most of which were relocated to the southern half of the country in previously-uninhabited areas, and 550,000 of them were Northerners. The second half (1981–1985) saw almost 1 million Northerners relocated to the New Economic Zones. Government and military personnel from Northern and North-Central Vietnam are also posted to various locations throughout the country that were often away from their home regions. More recently, the growth of the free market system has resulted in increased interregional movement and relations between distant parts of Vietnam through business and travel. The movements have also resulted in some blending of dialects and more significantly have made the Northern dialect more easily understood in the South and vice versa. Most Southerners, when singing modern/old popular Vietnamese songs or addressing the public, do so in the standardized accent if possible, which uses the Northern pronunciation. That is true in both Vietnam and overseas Vietnamese communities. Modern Standard Vietnamese is based on the Hanoi dialect. Nevertheless, the major dialects are still predominant in their respective areas and have also evolved over time with influences from other areas. Historically, accents have been distinguished by how each region pronounces the letters d ([z] in the Northern dialect and [j] in the Central and Southern dialect) and r ([z] in the Northern dialect and [r] in the Central and Southern dialects). Thus, the Central and the Southern dialects can be said to have retained a pronunciation closer to Vietnamese orthography and resemble how Middle Vietnamese sounded, in contrast to the modern Northern (Hanoi) dialect, which has since undergone pronunciation shifts. Vocabulary Although regional variations developed over time, most of those words can be used interchangeably and be understood well, albeit with more or less frequency then others or with slightly different but often discernible word choices and pronunciations. Some accents may mix, with words such dạ vâng combining dạ and vâng, being created. Consonants The syllable-initial ch and tr digraphs are pronounced distinctly in the North-Central, Central, and Southern varieties but are merged in Northern varieties, which pronounce them the same way). Many North-Central varieties preserve three distinct pronunciations for d, gi, and r, but the Northern varieties have a three-way merger, and the Central and the Southern varieties have a merger of d and gi but keep r distinct. At the end of syllables, the palatals ch and nh have merged with