Type A. Non-Roman to Roman conversions
A1. UN-approved romanization systems
A1a: Nationally and internationally implemented
rom.systems
A1b: Nationally implemented romanization
systems
A1c: Not implemented
A2. No UN-approved romanization systems
A2a: National systems + systems in other
countries
A2b: National system, no international use
A2c: No national system, various systems in
other countries
A2d: No national or known international systems
Type B. Roman to Roman conversion
Type C. Roman to non-Roman conversions
Type D. Non-Roman to non-Roman conversions