Based on the selected date, the application calculates the date on which 40 days, half a year and a year have passed since the death, i.e. the previous Saturday.

If the calculated date ends in the so-called "forbidden days" for memorial services, the application offers the first preceding permitted day and the first preceding permitted Saturday.

According to rule 169 of the Nomocanon, memorial services are not offered:
- during Twelve Days (from Christmas to Epiphany)
- the first week of Great Lent
- from Maundy Thursday to Thomas Sunday
- on all Christ and temple holidays ("red letter") and on Sundays.

The application is intended for priests and believers who celebrate Christmas according to the Julian calendar and Easter according to the Orthodox Church.

The application is informative. For specific cases, consult the competent priest.