In the dialog Parameters, at my new custom parameter (from a sketch), the option for exporting it as external is missing - how to get it now to the document's iProperties?
The solution is simple - with a single line iLogic macro you can copy the value of your custom parameter Cislo_znacky (tag number) to a custom property:
iProperties.Value("Custom", "Cislo_znacky") = Cislo_znacky
And the resulting iProperty value:
Then run this iLogic rule automatically at the appropriate time (on an event), e.g. before saving.
NOTE: you can also nest the command into a "try-catch" construction to avoid any errors