"double" is supposedly not a datatype in Kusto (Copilot says it is a synonym for "real"), but the gettype function will return it as a value...
gettype(123.45) -> "real"
gettype(cm.total) -> "double"
(where cm was a container of measurements used to contain a number of C# double values)
MS should either return "real" or mention "real" in the gettype documentation so programmers writing switch statements will realize that "double" is a possible value that should be handled.
