This event occurs just once before it display the search form. It can be used to set some default values to the fields. For example:
{company} = [glo_company];
Date fields are used differently, They use a suffix "day" for day, "month" for month and/or "year" for year. For example, The {Birth} field will be:
{Birth_day}=date("d");
{Birth_month}=date("m");
{Birth_year}=date("Y");