Primogeniture, in which the eldest child of the monarch is first in line to become monarch, is the most common system in hereditary monarchy. The order of succession is usually affected by rules on gender. Historically "agnatic primogeniture" or "patrilineal primogeniture" was favoured, that is inheritance according to seniority of birth among the sons of a monarch or head of family, with sons and their male issue inheriting before brothers and their issue, and male-line males inheriting before females of the male line. This is the same as semi-Salic primogeniture. Complete exclusion of females from dynastic succession is commonly referred to as application of the Salic law (see "Terra salica").