>I have a variable, m.FilterCondition, that is built as criteria is selected on the form. For example:
>

>m.FilterConditon = m.FilterCondition + " AND SomeValue = SomeOtherValue01"
>

>This works great until the same condition is selected again:
>

>m.FilterConditon = m.FilterCondition + " AND SomeValue = SomeOtherValue02"
>

>Now m.FilterCondition has both clauses, which causes problems. How can I ensure that I have a good conditional variable?

I use checkboxes. In InterActiveChange I set a property of the checkbox, something like this

If this.value=1
  cFilter=' somefilter '
else
  cFilter='.T.'
endif
Thisform.Setfilter()

Thisform.Setfilter:

Thisform.cFilter=thisform.chbCond1.cFilter + ' and '  + thisform.chbCond2.cFilter + ' and ' +  thisform.chbCond1.cFilter
Set filter to &thisform.cFilter