MLNEEDED fields

With the use of hidden mlneeded fields in your form you can specify
what fields the user of the form has to fill in before the mail
will get sent. The way mlneeded fields work is that one line specifies
a logical OR function for needed fields, and mlneeded lines relate to
other mlneeded lines in the form of a AND function.
In this way, all you have to do is look wat fields are needed, and than
use a litle basic boolean algebra to get a boolean needed function
represented as a AND function of or functions.

The best way to explain this is by example, lets say you have a form
you use to get feedback, and your form has the following fields:

firstname
lastname
citty
streetadress
postalcode
phone
fax
email

You could decide that you need the first and the last name, and also the
email address, and don't realy need the rest of the fields, this means
you could use the next mlneeded lines: 

firstname
lastname
email

Writable as : a . b . c

However, you could also decide that you need either a email adress, or
a fax, or a phone number (so you have always got one fast way to
get in contact with the person),than you could use something like:

firstname
lastname
phone,fax,email

Writable as : a . b . (c + d + e)


When however you say that you need just a way to get in contact with the 
person, if the person doesn't fill in phone,fax,or email, it should also
be ok if he would fill in the citty, the streetadress and the postalcode.
This however gives a function that is a litle more difficult,
this function would be writable as:

a.b.((c+d+e)+(f.g.h))
This is a verry common problem, but it looks more complicated than it is.
Using a litle basic boolean algebra this can be translated to:
a.b.(c+d+e+f).(c+d+e+g).(c+d+e+h)
So you end up with the following mlneeded lines: 

firstname
lastname
phone,fax,email,citty
phone,fax,email,streetadress
phone,fax,email,postalcode

You see that using the mlneeded mechanism, and a litle boolean algebra,
you can specify exactly what fields should be filled in before a mail
can be generated.

Error Numbers:

You should combine these values with error numbers, you could for example
define the following mlneeded fields:

mlneeded=firstname:02
mlneeded=lastname:02
mlneeded=phone,fax,email,citty:01
mlneeded=phone,fax,email,streetadress:01
mlneeded=phone,fax,email,postalcode:01
mlerrtxt_01="You didn't fill in your fax or e-mail or citty,street and postalcode"
mlerrtxt_02="You didn't fill in your name"

If both error 01 and 02 will ocur, the highest number is chosen