IS 20
Meaning under the Decree
The sign gives, for example, the direction and number of a cycle route, or how it runs at a crossing or junction.
294/2015 příloha 5
IS 21a IS 21b IS 21c Route marker for cyclists (ahead, left or right) 
IS 21d End of cycle route 
IS 22a IS 22b IS 22c IS 22d IS 22e IS 22f Street name or other public space name 
IS 23 Advance sign for a cultural or tourist destination 
IS 24a Cultural or tourist destination 
IS 24b Direction sign for a cultural or tourist destination