When I get the udef fields for an appointment, a stange value is in the list:
Alle Svar (2)
:DisplayText is the user visible representation of the value set on the UD field (so in case of a list, the list item name, for example). That has been included in the UserDefinedFields dictonary for a while.
Note: You should be using GetCustomFields(), the dictionary that contains both CRM UD fields and Service extra fields, the values in that dictionary take priority over UserDefinedFields.
Unfortunately the API's pollute some response data with properties containing a second colon in the name for the SuperOffice web client purposes only.
These can be safely ignored.
To set the custom object field, use the "SuperOffice:6" property only.
The following should be ignored:
{PropertyName}:DisplayText
{PropertyName}:DisplayTooltip
Sorry for the inconvenience.