Under the Vietnam Labor Law, all foreign workers who work in Vietnam for more than three months must obtain a labor permit. You must get a work permit before you get a work visa.
Work Permit Issued(Work Permit)
Issuing temporary residency
Visa issuance in Vietnam
DT - Foreign investors entering Vietnam for investment
DN - Workers in Vietnam
LD - the person who enters for employment
DL - A person who enters for tourism
TT - LV1, LV2, TX, NN1, NN2, DH, PV1, LD Family with accompanying visa