There are two different meanings of the word day
Varsha, Masa, Dina and Hora are only defined for the the astrological day.
The time from sunrise to sunset is divided into 12 equal parts (the day) and 12 parts from sunset to next sunrise (the night). The first Hora lord of the day is the day's lord. The other lords will follow in their order:
Saturn - Jupiter - Mars - Sun - Venus - Mercury - Moon - etc.
The sublords for sunday are
For the day: Sun - Venus - Mercury - Moon - Saturn - Jupiter - Mars - Sun - Venus - Mercury - Moon - Saturn (12)
For the night: Jupiter - Mars - Sun - Venus - Mercury - Moon - Saturn - Jupiter - Mars - Sun - Venus - Mercury (12)
There are at least 2 other views about Hora calculation (currently not supported by Maitreya)
Varsha lord can be calulated if we have the year of the date. The rule is
varshaLord = (( year + 3 ) * 3 ) mod 7
where the planets are in their natural order (Sun .. Saturn), i.e. zero is the Sun, 1 is Moon etc.
Example: The year 2004 yields (2004+3) * 3 = 6021, divided by 7 yields 1. So Moon is the lord of the year.
The table below gives examples for Varsha lords of several years.
Masa lord can be calulated if we have the year and month of the date. The rule is
masaLord = (( 12 * year + month + 6 ) * 2 ) mod 7
where January is 1 and the planets are again in their natural order (Sun .. Saturn).
Example: November 2006 yields (12*2006 + 11 +6) * 2 = 48178, divided by 7 yields 4. So Jupiter is the lord of the month.
The table bellow gives examples for Year lords of several years.
Dina lord is the weekday lord of the ordinary calendar, i.e. Sunday's lord is the Sun, Monday's lord is the Moon etc.