Therefore API > API Reference > Classes > TheIndexData > Methods
SetCategory
Sets the category for the document.
Name
Description
SetCategory (string, TheServer)
Looks up the specified category name on the server and sets the category number accordingly.
SetCategory (int, TheServer)
Sets the category number.
SetCategory (TheCategory)
Copies the category number from the specified TheCategory object.
Please check the help pages of the various overloads for the exact syntax in Visual Basic and C#.