can't we use on.old.occ in User exits?
its giving error unresovled reference to on.old.occ
if no then how do achieve to get old values and verify if particular field changed or not?

ok got it
with.old.object.values.do

Also, You could verfiy whether a field is changed or not with dal.is.field.changed()


Syntax:
function boolean dal.is.field.changed (string fld.name [, long element])

Description

Use this to test whether a field has changed. It is equivalent to:

dal.get.field.mode(fld.name, [ element ] ) <> 0


Arguments
string fld.name A string containing the field name

[long element] Optional element, use this in case of array elements


Return values
TRUE in case the field has changed, FALSE in case the field has not changed.

Context
This function is implemented in the 4GL Engine and can be used in all script types.

i need to act further based on old.value also so
i need to use with.old.object.values.do
Any how thanks for the suggeston Ajesh for this
which i can make use next time when needed.