why the usage for decimal must be comp-3

[yimwai]

using CFF stage to read an EBCDIC file , I want to set default value for one column. But The message box show up (usage for decimal must be comp-3) i wanna know why? if I set usage to comp-3 the result data would be incorrect(reading less bytes for the column)

ps. another problem: If usage has been changed to comp-3, it cannot be set back to display

[chulett]

A continuation of this post for those following along in the home audience.