% dimensions of the problem
N=46; % number of spatial units
T=6; % number of time periods
K=3; % number of explanatory variables, constant should not be included
m=63; % Value that indicates the period of time between the first observation in the sample and the moment the process being modeled has started in the past

请问大家m=63；%之后的 这段话是什么意思啊，63是怎么来的？请各位大神赐教