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
