Adding a multi person select field to your fields.xml

While I was googling to add a multi person field to a feature I noticed quite a lot of problems of getting them to actually use multiple persons.
The solution to this is to set the attribute mult to true like this:

< Field
Type="UserMulti"
DisplayName="The display name"
Description="Your description"
Group="Custom Columns"
ID="{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}"
List="UserInfo"
MaxLength="255"
Name="NotificatieAan"
Required="FALSE"
RowOrdinal="0"
Mult="TRUE"
ShowField="ImnName"
SourceID="http://schemas.microsoft.com/sharepoint/v3"
StaticName="InternallyUsedName" />