Hi,
Any type of condition record will get valid date automatically from the date you change any parameters of that record.
Ex: Existing record Mat1 - 1Ea- $100 validity 01 01 2013 - 31 12 9999, then you changed price on 30 08 2013 then condition record validity will be like below automatically.
Mat1 - 1Ea- $120 validity 30 08 2013 - 31 12 9999.
But for exclusive change of validity period also can be done like below
R,
Amala