* Calculation of ages in Facts

[bp158]

I have been inputting education facts for students at Oxford and I am finding the following:
Born 1797
Education: Christchurch
Date 1815-1822 (converts to 'btw1815 and 1822)

In the facts box it shows
1815-1822 Educ. Christchurch 17-25

Should it not read 18-25?

Barbara

ID:6119

[LornaCraig]

No, because he could have been born in December 1797 and started the education in September 1815 when he was 17 years and 9 months.
When dates are given only in years FH calculates the maximum possible age range.