{office-formula]Why is TDIST a "right tail" type?

Hi members,

in the definition of TDIST the missing integral has been added recently. 
But I'm wondering, that it is a "right tail" type. All other cumulative 
distribution functions are of "left tail" type. CHIDIST and FDIST, which 
are right-tailed in some application, where made LEGACY to get 
consistent definitions. I have expected, that the same would be done 
with TDIST.

kind regards
Regina