- session_id [xsd:string]
 - Your API session id.
 - field_name [xsd:string]
 - The field name to edit
 - new_width [xsd:string]
 - 
                          The field new width to be updated.
Allowed widths “small”, “medium”, “large” - truncate_data [xsd:boolean]
 - 
                          Truncate data is used along with the custom list field width when decreasing a custom list field size.
It is ignored when increasing the custom list field width. 
