I wouldn't say it's compulsory... it's only that there are internationally defined abbreviations for the different countries in sports or as nations... This means CH identifies confoederatio helvetica as country Switzerland - it's SUI in sports. This is just like putting an F for France or D for Germany or GB for England... but in sports the abbreviations would be different.
CH is the abbreviation of Switzerland's official name Confederatio Helvetica.
The two-letter country code "CH" represents Switzerland.
CH - from Confederatio Helvetica in Latin
If you mean the international car registration then it is Switzerland
Switzerland - official name: CH, confoederatio helvetica
Switzerland
Switzerland
Switzerland
Switzerland.
Switzerland
Cars in Switzerland have "CH" on them because "CH" is the country code. It stands for "Confoederatio Helvetica", or "Swiss Confederation".
CH is the international badge for Switzerland, or Helvetia.