$INCLUDE <Filename>$INC <Filename>
Includes a Timetable file with the file name <Filename>.
This functions as if the entire contents of the file <Filename> appear at the place
where the $INCLUDE line appears.
There is no maximum limit to how many files can be included into another Timetable,
but the number of nested include statements cannot exceed ten.
That is to say, if you include a file, it can contain an $INCLUDE as well and so on
up to a depth of ten levels.
If you use relative path names, they will be evaluated from the path of the timetable file
the $INCLUDE is in.
If you build a complex include structure, check out the $REQ, $REQUIRE commands too -
they can avoid including the same file more than once.
For using $DEF macro definitions, $POOL definitions from several different timetable files,
sometimes starting them individually, in other cases using all of the from another
timetable file including them all $REQUIRE command provides an opportunity to
run through the definitions only once (which sometimes only save times, but often avoids
syntax errors having multiple definitions of the same $POOL name, for example).