PEAK XOOPS - A wrong designed class "Criteria"

Criteria is a class for XOOPS.
eg.

This Criteria does not have data type for the value.
Thus, all values should be considered as string.

But some patterns of value will be considered as the other type.
It's a critical design.

If Criteria will be used XOOPS continuously, it should be added a parameter for specifying value's type.