I load a form on startup that is hidden
e.g. DoCmd.OpenForm "frm_VariableStore", , , , , acHidden
Have a text box for storing variables and refer to them by
forms!frm_VaraiableStore!txt_Var1 = ### etc
then in the query place
> forms!frm_VaraiableStore!var1 and < forms!frm_VariableStore!var2...