You are on the right track... The 1 indicates that it is a required field. In your case the first two select boxes should probably be required but the last one (Details) should not be required as it may not contain any values
This is what you should have for the 3 select tags:
<select name="Restaurant" size="3" id="Restaurant" eform="::1::#LIST maarssen,hth">
<select name="Feest" size="2" id="Feest" eform="::1::#LIST SShappy,SSfeest,SSthema">
<select name="Details" size="2" id="Details" eform="::0::#LIST princessje,piraat">
I’ve tried out your form with this and these are the results (from debug output);
’formid’ passed using rule: #VALUE eKinderfeestjesForm, (input=eKinderfeestjesForm)
’Restaurant’ passed using rule: #LIST maarssen,hth (input=hth)
’Feest’ passed using rule: #LIST SShappy,SSfeest,SSthema (input=SSthema)
’Details’ passed using rule: #LIST princessje,piraat (input=piraat)
’dow’ passed using rule: #LIST Maandag,Dinsdag,Woensdag,Donderdag,Vrijdag,Zaterdag,Zondag (input=Dinsdag)
’geslacht’ passed using rule: #LIST jongen,meisje (input=meisje)