Current traffic control system does not use calendar.txt table at all. All trips are expressed as exceptions in calendar_dates.txt to base state of calendar.txt where no lines are driven ever. Currently you can omit calendar.txt altogether and pick dates for trips from calendar_dates.txt only.
{
"A:F\u00d6LI_Kes\u00e4_2015_ver3": {
"monday": false,
"tuesday": false,
"wednesday": false,
"thursday": false,
"friday": false,
"saturday": false,
"sunday": false,
"start_date": "20150601",
"end_date": "20150628"
},
/* ...(snip)... */
"S:F\u00d6LI_Kes\u00e4_2015_ver3": {
"monday": false,
"tuesday": false,
"wednesday": false,
"thursday": false,
"friday": false,
"saturday": false,
"sunday": false,
"start_date": "20150601",
"end_date": "20150628"
}
}