TIMEOUT (loexpr,testexpr,hiexpr)

Returns time tag for the first step in the current
processing period where the value of 'testexpr' is
either less than 'loexpr' or greater than 'hiexpr'.
I.e. returns the time when 'testexpr' first breaks
out of the band defined by 'loexpr' and 'hiexpr'.
See FUNCTIONS notes.
