Time dependent string options accept a string of text with optional variablity in time. In the simplest form this is just a constant string for all time.

Constant text
--switch=Value

If the option contains a / then it is treated as time dependent. In this context the value is split into fields separated by , with the first field being the interval and all further ones specifying the time range. This means that the string in the first field is the value for the time range specified in subsequent ones.

Time dependency
--switch=First,,2016:10/second,2016:10
--switch='Zero,,2016/One,2016'