How to set the FACTS file?

[gored24]

What is the format of mw94_n22_nz_ha.xyt：
Initial Cond. (0:FLT,1:File,2:WM,3:LS,4:FLT+LS): 0
Specify BC (0-Open;1-Sponge;2-Wall;3-FACTS) : 0
Specify Input Z filename (for BC=3, FACTS) : mw94_n22_nz_ha.xyt
Specify Input U filename (for BC=3, FACTS) : mw94_n22_nz_ua.xyt
Specify Input V filename (for BC=3, FACTS) : mw94_n22_nz_va.xyt